820-00597 locks up after short time during boot

[2informaticos]

First of all, welcome to the forum!

Possibly bad GPU.
However, try new BIOS.

820-00597-A Clear ME.bin

drive.google.com

820-00597.rar

drive.google.com

Let me know if any works for you.

BTW, don't forget to make backup first!

 

[tbaker2500]

Thank you! I'll look up how to flash this BIOS and try it out.

 

[tbaker2500]

It's U5210 I need to reflash, right?
Looking for a WSON adapter or I'll just solder wire onto chip pads I suppose.

Did a little more experimenting with it. Tried heat and cold around the GPU, no major differences.

It's booting into one of 3 states:
1. External monitor works, chimes, locks up 1/3 of the way on the boot bar.
2. External monitor doesn't work, chimes, no idea how far it gets because no monitor.
3. No monitor or chime.

Thanks!
Tom

 

[tbaker2500]

Okay, I reflashed the chip with this bin file after saving a backup. Programmed and verified successfully. Doesn't boot, only get the first diagnostic LED. Is there a chance I got the board number wrong? I was inferring it from google searching for this iMac, A1418 EMC 3069.

 

[2informaticos]

The code is marked on the board.

820-00597-A 3.0GHz i5 Radeon Pro 555 2GB Logic board iMac 21" Retina A1418 4K 17 | eBay

Radeon Pro 555 2GB. Logic board details 1x SDXC Card Slot.

www.ebay.com

Check the 5th picture.

 

[tbaker2500]

Thanks. Yes, that's the same model number on mine.
I had no trouble flashing the chip, verified correctly. Checked all the solder connections, it ohms out properly. Are there any special steps I should do to make this clean ME version of the EFI work? Should I just dump the old data back in?

 

[2informaticos]

Check if you can find another dumps on Internet.

 

[tbaker2500]

Found another dump which functioned. Unfortunately, the problems persist. Worth a try, but not related to a BIOS corruption.
What's a good next step?

 

[2informaticos]

Probably GPU internal failure...