AI PCs

We have an HP All-in-One 24-dp0158qe with the original power adapter which will no longer power up correctly,     It goes immediately to the loud beeps (3 long, 4 short) which someone accurately described as like an Amber alert.    After 5 iterations of that, we get a black screen showing "unsupported adapter installed".      I've read all the other posts about disconnecting the power and removing the battery, etc.    We tried that and let it sit for hours, but that did not solve the problem.   We replaced the battery on the motherboard to see if that would help, but it did not.    We tried removing everything from the motherboard that we could disconnect (wireless card, 2nd hard drive, ...) and that had no effect.   We even borrowed a more powerful power adapter from a different HP All-in-One , but that didn't help either.      And, as always seems to be the case, this machine is no longer covered by a warranty.

We did find that if we hit ESC when the black screen comes up, that we can run all the diagnostic tests.    Those tests all run clean with no errors.   We can also hit ESC and choose to go into the boot menu.   When we do that, and then simply exit the boot menu with no changes, Windows boots up normally and everything seems to be working fine.     

Does anybody have any additional ideas on how to get past the alarms and the error message?