820-00426 fails to boot with trackpad connected

[ThisIsWes:AASP]

I have two of these boards now with the same issues. They crash about 25% into booting. If trackpad is disconnected they will boot fine.
tried both in good cases and they still fail to boot.
Ive seen older posts about this but they weren’t resolved.

 

[2informaticos]

Machines restart, or stay off?

 

[piernov]

Known good battery?

 

[ThisIsWes:AASP]

They both restart. 15 seconds.
Yes good battery.

 

[2informaticos]

Remove/replace U4850 and test again.

 

[ThisIsWes:AASP]

Same after replacing u4850.

 

[2informaticos]

Did you test without U4850 first?

 

[ThisIsWes:AASP]

I misunderstood. Just tried and still does the same with u4850 left off.

 

[2informaticos]

Try starting Apple Diagnostic mode.
See if any error pops up.

 

[ThisIsWes:AASP]

With or without u4850?

 

[ThisIsWes:AASP]

Diagnostics won’t run. I can select a language and agree but the progress bar never comes up and the courser freezes.

 

[ThisIsWes:AASP]

The other Mac allowed me to run diag. Came back no issues.

 

[2informaticos]

Try another battery, tested in other machine for sure.
Also try starting in safe mode.

 

[ThisIsWes:AASP]

Out of other batteries. Used last one I used was working with another machine.
safe mode doesn’t work.

 

[ThisIsWes:AASP]

Ordered an aftermarket battery. If that was the issue would an aftermarket battery even resolve it?

 

[2informaticos]

Always good to have old original batteries in stock, just for test.

 

[ThisIsWes:AASP]

So another new battery and both boards booted no problem. Strangely, I put them back in their original cases and they worked with those batteries now.

The trackpad threw me off with these. That and I had to go through 3 ‘good’ batteries to make it work.