my onn tv wont switch on tho there is power?

my onn tv has been having problems switching on if i switch it off by the mains supply. it works fine when you use the standby function, never had no problems there. a few months ago there was a power cut and when the power came back on the red light on the telly was flashing, it had never done this before.
after about half an hour it came on again.

it has happened a couple of times now but this time i have waited for about 8 hours and its still not come on?