Hi,sorry for the delay but to crown it all off my laptop decided to come out in sympathy with my tv and shut down refusing to boot up.Got sorted so here's the info you needed;
Model No: 42AV554D
No it won't switch on manually,the power light is solid only blinks if I try to switch it on using the remote,blinks once as if trying to turn green then stays solid.
Thought as much and if it's a matter of plugging in a replacement board I'm keen to give it a go,i.e. with your expert instruction.Please advise.
I'm in your capable hands
Thanks a lot Anthony,looking forward to a bit of tech investigation.