Sony TV KV-36FS76U error code 5 blinks

Question

Sony KV-36FS76U error code 5 blinks (AE5A chassis)
Please can you help me with this TV.
I just got this TV from a guy who has been using it for a year keeping it alive by playing a fan on the back. I found that it would also work if the back was removed.If not it would switch off after a few minutes with error code - 5 flashes. With the set running I put the back cover back on and within about 4 minutes it tripped. I considered which part could be so dramatically effected so quickly and concluded that the PCB on the tube (the C board) would be the one so simulated the effect by putting a dry cloth over this PCB. Within about 1 minute it tripped. However now there is no video at all. Thare is sound for about 10 secs then it trips and the error code is still 5 flashes. I find it hard to believe such a minor action could have damaged it. If I disconnect the C board it does not stop the set from tripping. Also If I disconnect the 2D board that carries the LOPT it still trips.

I can be Emailed at chris.<nospam>lowdon@ntlworld<removetextinbrackets>.com