Grub2 start boot page/menu boot page blank when starting Zorin 16 lite

I recently repartitned the 256GB Toshiba HDD on my mid 2010 Mac Powerbook to install Zorin 16 lite to test drive it before upgardig. When booting after successful install, the Grub2 boot page shows only one '-' without menu choices to boot from. I expect to see the 1st entry for Zorin lite and 2nd choice to be Mac OS X but that doesn't appear. The hardware is as follows:

Communications

  • AirPort Extreme Wi-Fi wireless networking2 (based on IEEE 802.11n specification); IEEE 802.11a/b/g compatible
  • Bluetooth 2.1 + EDR (Enhanced Data Rate) wireless technology
  • 10/100/1000BASE-T Gigabit Ethernet (RJ-45 connector)

Audio

  • Stereo speakers with subwoofers
  • Omnidirectional microphone
  • Combined headphone/line in (supports digital output)
  • Support for Apple iPhone headset with microphone

Environmental Status Report

MacBook Pro is designed with the following features to reduce its environmental impact:

  • Highly recyclable aluminum and glass enclosure
  • Mercury-free LED-backlit display
  • Arsenic-free display glass
  • BFR-free
  • PVC-free3
  • Reduced packaging volume
  • Meets ENERGY STAR Version 5.0 requirements
  • Rated EPEAT Gold4

Acoustic Performance

DECLARED NOISE EMISSIONS in accordance with ISO 9296

Sound Power Level
LWAd (B)
1 B = 10 dB
Sound Pressure Level
Operator Position
LpAm (dB)

2.4 GHz 2.66 GHz 2.4 GHz 2.66 GHz
Idle 2.8 2.8 17 17
Hard drive accessing 2.8 2.8 16 16
CD drive accessing 3.4 3.4 30 26

  1. LWAd is the statistical upper-limit A-weighted sound power level (rounded to the nearest 0.1 B).
  2. LpAm is the mean A-weighted sound pressure level measured at the operator position (rounded to the nearest dB).
  3. 1 B (bel) = 10 dB (decibel).

Display

  • 13.3-inch (diagonal) LED-backlit glossy widescreen display with support for millions of colors
  • Supported resolutions: 1280 by 800 (native), 1152 by 720, 1024 by 640, and 800 by 500 pixels at 16:10 aspect ratio; 1024 by 768, 800 by 600, and 640 by 480 pixels at 4:3 aspect ratio; 1024 by 768, 800 by 600, and 640 by 480 pixels at 4:3 aspect ratio stretched; 720 by 480 pixels at 3:2 aspect ratio; 720 by 480 pixels at 3:2 aspect ratio stretched

Graphics and video support

  • NVIDIA GeForce 320M graphics processor with 256MB of DDR3 SDRAM shared with main memory5
  • Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on an external display, both at millions of colors
  • iSight camera
  • Mini DisplayPort

Pure digital video output

DVI output using Mini DisplayPort to DVI Adapter (optional)

VGA output using Mini DisplayPort to VGA Adapter (optional)

Dual-link DVI output using Mini DisplayPort to Dual-Link DVI Adapter supports 30-inch Apple Cinema HD Display (optional)

HDMI output using a third-party Mini DisplayPort to HDMI Adapter

Input

  • Full-size backlit keyboard with 78 (U.S.) or 79 (ISO) keys, including 12 function keys and 4 arrow keys (inverted “T” arrangement)
  • Multi-Touch trackpad for precise cursor control; supports inertial scrolling, pinch, rotate, swipe, three-finger swipe, four-finger swipe, tap, double-tap, and drag capabilities

Processor and memory

  • 2.4GHz Intel Core 2 Duo processor with 3MB on-chip shared L2 cache
  • 1066MHz frontside bus
  • 4GB (two 2GB SO-DIMMs) of 1066MHz DDR3 memory

Storage

  • 250GB Toshgiba 5200rpm SATA
  • 8x slot-loading SuperDrive (DVD±R DL/DVD±RW/CD-RW)
  • Maximum write: 8x DVD-R, DVD+R; 4x DVD-R DL (double layer), DVD+R DL (double layer), DVD-RW, DVD+RW; 24x CD-R; 10x CD-RW
  • Maximum read: 8x DVD-R, DVD+R, DVD-ROM; 6x DVD-ROM (double layer DVD-9), DVD-R DL (double layer), DVD+R DL (double layer), DVD-RW, DVD+RW; 24x CD

Battery and power7

  • Up to 10 hours wireless productivity
  • Built-in 63.5-watt-hour lithium-polymer battery
  • 60W MagSafe Power Adapter with cable management system
  • MagSafe power port

I need help boot to the original IOS operating system to complete data retention to the new Zorin system I just installed. I'm able to see And get into the old IOS partition from Zorin however, the folders are password protected and no password entry is prompted when attempting to open these folders.

Your expedience will be greatly appreciated.

Did you use rEFInd during the installation?
I am not sure if Boot Repair applies in exactly the same way on MacBook:

No, I did not. This is the second Mac I've done over the last twenty years with LINUX of all flavors. The 1st was a 16 year old MacBook with Lubuntu. However, it appears that now the MacBook Pros are showing up since Apple doesn't support many of them now. This Debian/ubuntu distro install has been quite limiting and different for Zorin. Unbenouced to me it installed 'Snap' and 'Fatpak'. Not a big fan of 'Snap' yet. Zorin doesn't allow the end-user to make some, what I think, necessary install choices.

...I agree with you. Snap and Flatpak are being pushed, heavily, by Canonical / Ubuntu.
Zorin OS steers toward easing windows users into Linux and it is perceived that Snap and Flatpak are easier to use for installing.
Personally, I think they create new problems. The concept behind Snap or Flatpak may be fine, but the implementation is poor, very intrusive and... it seems to me... exploited for other purposes.
I am a noob or a newcomer to Linux myself. I came into Linux after much of what today would be considered, classical FOSS Linux. In doing so, as someone caught between two worlds you may say, I am witnessing alarming and widespread abuses in Linux that span a large number of threads on this forum.
From what Gnome has become, the limitations placed in gtk4 and Gnome 40, Canonical, Snap, Systemd, Wayland- Proposed solutions to problems seem to come with heavy caveats of price: Many are geared toward impressing the user with a Better System, but in actuality are perverted toward re-assigning control away from the user and to the developer.

For me personally, this is a draw toward Zorin OS. Other newcomers to Linux often stop by here first. And this allows them to be exposed to many ideas and perceptions, rather than being inundated with only one perception or point of view.
Linux is great. But in many ways, is prone to the same damages that Proprietary Mac and Microsoft are.
Though, my apologies... We seem to have gone off topic from your original problem...