3 Beeps RAM repair gone wrong...?

This is an obvious answer, but HOW do we check soldering that is under a chip that we re-balled? We will reflow them all again to see if it cured anything.....

If you don't have access to X-ray, the practical options are pretty limited. I'd check for proper PP1V35/PP1V5 RAM power, verify all RAM related enable and reset signals, and inspect for any bridged or missing pads around the chip edges. If those look good, I'd reball one RAM chip at a time rather than reflowing them all together, since a single misaligned or open BGA joint is enough to leave the board completely dead.

@mrdoom3412 OK I will go over it with what you mentioned and get back to you with my findings, it may need a few days. Thanks!

@livfe - A friend of mine who does expensive electronics system repairs picked up from a closing dentist their Digital X-Ray system for $1500!!

For this exact reason as it's so tough to know if a pads solder ball shorted across two pads. He made an X-ray proof box to house the emitter and a way to hold the detector plate where he needed. His clients love the fact of getting the printout of the X-Ray of the repair.

@danj Buying an X-Ray machine for $1500 to fix a $50 2012 MacBook air, sounds like a great idea if you have the type of business to support it, but as for me with maybe 2 old worthless MacBooks it doesn't make much economical sense to me.... Local hospital might help as they have X-Ray but they won't entertain the idea to X-Ray a MacBook and would likely laugh at the idea even. Never mind, I think this one is beyond my skills or patience to waste more time on. Needs an SSD anyway and they are hard to source and I am not buying a new M2 & converter as the sale price of the working unit would be less that the price of the SSD.