Just me.... but a "first couple of things" I would check would be:
1- Power. Find and check all the power supply test points just to make sure you aren't fighting something simple that is common to all/many circuits.
2- My SAMS shows this unit uses a PLL02A for the PLL chip. Check pin 6 (LD) with a DMM or scope. If it is low, the PLL is not locked and most of the time nothing will work. Looking at the schematic it looks like this radio only kills "TX" if it is not locked. But, if it is NOT locked... who knows WHERE the VCO is oscillating.... if at all!
And ... if the power supplies good, it might be a good idea to chase the "no PA" problem first.... as it is STRICTLY audio. If that isn't working you won't get any sound at all... which seems to be what you have. You'd just have to check ....
mic jack -> audio amp -> speaker.
You might also want to check the microphone/microphone wiring. The RCV pin grounds the speaker when the speaker is supposed to work. If the mic doesn't ground that pin... the speaker won't emit sound. I realize this won't affect the PA checkout... I am assuming that you had a speaker plugged in the PA jack when you tested that...
These are some "low hanging fruit" that I think would be a great place to staIrt.
Bob