5D MkII does not turn on with ML card

[daniu]

I have spent a lot of time today reading the forums and trying to troubleshoot this to no avail.

I have followed the procedure of putting the extracted nightly build files onto my CF card and running the firmware update. The green message comes up telling me it was successful and to restart my camera, but when I try my camera no longer boots (or shows any sign of life) as long as there is a ML card in it. Camera still boots totally fine with no memory card or with a formatted non-ML card.

Would love some help on this!

[Walter Schulz]

Are you using an SD-to-CF adapter? If so: Don't!

First things to try: Turn off camera.
Remove battery, insert ML card. Insert battery.
Power up camera.
If not working: Remove battery, remove card.
Insert card into cardreader and format card.
Insert card and battery and format card in cam.
Redo installation steps from here and report back.

[daniu]

Took all steps but same results with reinstallation. Camera still only responsive without ML in it.

[Walter Schulz]

Check ML\LOGS\
Do you have ROM0.BIN and ROM1.BIN there? If yes: Backup those files.

[daniu]

I have them backed up from the first time I tried the installation.

[Walter Schulz]

Good!
CF-Card used? Link pic, please!
Which OS is running on your PC?
Do you have one (or more) spare card(s)? If so: Have you tried with that one, too?

[daniu]

I was initially using the 64gb card but then read that that would not work for initial installation. Since then I have been trying on the 512mb card. Exact same outcome for both.

I am on Mac, running Catalina 10.15.7.

[Walter Schulz]

Looking good. Install issue with high-capacity cards should not occur anymore. Install routine has changed.
There are a few things left to try but I'm quite convinced they won't change anything. As far as I can see you did nothing wrong.

Waiting for a1ex to take over.

[a1ex]

Indeed, it's a bit of a mystery, and here's why:
- Card formatted from camera. Check.
- Bootloader able to load FIR file from card. Check.
- Our installer FIR able to check for existence of AUTOEXEC.BIN and ML folder. Check.
- Card is made bootable. Check.
- Bootloader unable to load AUTOEXEC.BIN from card?! This is where it normally locks up with no apparent signs of life - see this flowchart.

One way to troubleshoot this would require access to UART. Not sure where the pins are on 5D2, but I can check if needed. Requirements: FT232RL module (USB to serial) + needle + Arduino-like electronics skills.

Another way to troubleshoot this would be by running QEMU on Mac directly from the physical CF card. I can assist with that, e.g. on Discord or IRC or Teamviewer. We might have the surprise to find ML booting in QEMU from the physical card, but having trouble doing so on the physical camera - in that case, the only way to diagnose this might be the UART port.