Thanks Ty, looks like it is pin 26 on the mega8 for the PIR, going to carry out a few checks later today, just strange that it was all working for hours, then not, hopefully a loose connection. I did notice that the header pin connectors were a bit loose, so possibly an issue there.
It really sounds like a bad soldering joint somewhere where heat causes this problem. I would suggest to quicky resolder all joints on the PCB and cables. With a 300 degrees Celsius small soldering tip quickly melt all soldering joints, Apply a little bit extra solder where necessary. Also change the power supply with another one (with the correct voltage and current output). Also post a high-res picture of the front and back of PCB (as high-resolution as possible).
Thanks Ty, new PSU ordered.
I have noticed the current supply, sometimes I had to unplug and plug back in to get the clock powered up. Also I did have a very hot mosfet, Just switched off and on and it resolved itself. I didn't know if you swap PSU's you had to factory reset, so thanks for that.