Problem with Sanyo PLC5605B - help!

I am trying to fix this Sanyo 5605 but it's got me pulling my hair out (and there's not much left!)
Switch it on and it starts in standby. Start it up and the lamp comes on for approx 2-3 seconds with the logo then it goes into standby again - it then has to be completely powered off to be able to repeat the process.

I have cleared the filters, the fan is clear and running and even swapped the lamp with a new one.

Can anyone please give me some clues as where to look ?

I normally fix tubed projectors and unfortunately do not have a manual for this baby.

Thanks in advance.

Scoobie