I had that same problem, wouldn't power on, and it's probably from taking too much current somewhere in the radio unit. I removed all circuit boards and took a look and then put them back in. It then powered up but the BFO oscillator are dead so no SSB mode. It was probably some component in that BFO that short circuit but later broke in a way that it no longer took any excessive current.
In my R2500 they have put the wrong capacitors on the VCO voltage control line so there's an added noise from the PLL stepping back and forth in frequency while stationary on a frequency. It's a known problem that have been reported by users and somebody at the factory probably put the wrong reel of components in the machine that place the components on the board. It could then also be a higher value capacitor placed in its wrong polarity that after some time makes it stop working, short circuit and then go open.
/Ubbe