2020 M1 MacBook Air 820-02016 with startup issues

[sekidata]

This A2337 Air came in "water-damaged", but the only evidence of liquid exposure was on the USB-C plugs, which were badly corroded. With a fresh USB-C board, the machine chimes but only shows a blank screen (backlight is on). On an external display, the screen flashes on and off, showing the cursor on a black background. Intermittently, the machine will display and attempt startup and I've gotten it to load Recovery Assistant once (and verified that the machine does not have activation lock).

I've tried A DFU Restore, which successfully ended in a padlock on the host (but no video on the target Mac).

Do you have a BIN file for reflashing the SoC ROM?

 

[2informaticos]

I don't have known good SoC ROM for any M1 MacBook.
You can find something on badcaps forum, I think.
However, it should be good, if completed DFU.

You've got image on internal LCD, or external monitor?
You may have accumulated crap underneath BGA chips.

 

[sekidata]

Ok, so I'll assume the SoC ROM is fine.

The machine just started up for me on internal display and let me install an OS. But on the next restart, the display reverted back to black. When I unplug the internal screen, I get an external display image but it comes and goes at random intervals (sometimes displaying for several seconds, then disappearing and reappearing). Interestingly, it shows the internal display as connected even though I unplugged it, see below. Could this be a GPU issue?

 

[2informaticos]

Did you ever get image on internal LCD?

GPU is embedded into M1 CPU.
It may have accumulated crap underneath.

 

[sekidata]

As I wrote, the internal LCD works sometimes. It displayed all the way through OS installation, but on the next restart remained blank.

Is it worth risking a reflow of the M1? The board looks very clean - no liquid or other damage.

 

[2informaticos]

You don't need to melt the CPU's balls.
Only need to burn eventual crap.

 

[sekidata]

I tried heating up the M1 for 2 minutes at two different temperatures and neither changed the situation. Same as before: internal display is backlight-only; external display works intermittently. Any other ideas?