Quick Repair: Change the
- fuse (2AT)
- High side rectifier bridge (replace with something that can withstand 230VAC)
- ZD2 (check if its shorted)
ZD2 might have blown off the PCB as well. It seem to be there to protect the gate of the switching transistor as the driver can output a higher voltage than VGS(max). I had a small 18V Zener in a bag and that worked. Not sure what should be there really. Cathode should be towards the transistor Gate.
The red led should lit up when no battery is connected.