Failure to come on suggests PSU as a likely candidate, though not the
only one.

But you need to be aware of the various dangers in TVs before poking
about. Theres caps that store mains V, live lines on boards, 25kV EHT,
with storage in the tube, and one or 2 HT lines as well for eg focus
(maybe a few kV) etc. Plenty of ways to cook.

NT