lg flatron tv user manual
If I had to guess, I would suspect the degaussing circuit. The degaussing coil is connected in series with a PTC resistor. This PTC resistor gets hot and quickly limits to current through the degaussing coil. Degaussing only occurs on cold starts.
My guess is that the degaussing coil has a short in it. The coil draws way too much current and trips the breaker. However, before the breaker tripped you built up some heat in the PTC. Therefore, if you reset the breaker and then repower the set, it may turn on.
Unplug the degaussing coil and see if the problem goes away. If it does, then you know the problem is in the coil circuit. (The degaussing coil demagnetizes the CRT. It usually has a two pin plug attached to the power board. The coil itself is clipped around the edge of the CRT.)