The battery read 3.2 volts so I think its fine. Nothing in the manual helps. The left side of the display says 300.450 with the 450 flashing. The right side says 0.20.000 with the 000 flashing. I have done both a soft reset and a hard reset. Nothing changed. The control buttons seem to work. I can press rev and it goes there. The mike seems ok. I don't have any audio coming from the speaker either. Volume at full and the squelch open.
Check mods.uk. There was a mod to free tx/rx frequencies in those 5100/5200. If your's have the mods, then check them or undone them.
Now, whenever you reset the radio (I think it was a 3 key combo + power up) you have to set the limits. In this order (from the top of my head, check a manual):
- UHF lower rx freq.
- UHF upper rx freq.
- UHF lower tx freq.
- UHF upper tx freq.
- VHF lower rx freq.
- VHF upper rx freq.
- VHF lower tx freq.
- VHF upper tx freq.
Move the encoder (you can press MHz to speed up) to set the freq. and press D/MR. Repeat until all done.
I think the inital values after reset are 200 or 300 MHz for UHF, and 20 MHz for VHF, so at least that last is a coincidence. The receiver is not great far away up or down the band (indeed, the UHF receiver is not great even in band) and check that the tx limits are in-band.
73 de Fer