I have a sony KV-30HS420 CRT HD television whose menu keeps flashing on and off. I'm not sitting on a remote anywhere, and I've disabled all the signals in the house that I think might be interfering with it, but it still does this. Sometimes it flips on, then stays for a while, then flips off. Other times, it's like there's a crazy child pushing the button as fast as he can, but the button seems to be normal.

The button is not normal anymore if you could only pull it out to the pcb and try to test it using a tester you will notice that it has already a resistance. Lets first make this simple if you have a electronic contact cleaner try to apply it, then push it as the contact cleaner in the tact switch, to clean the contact of your switch, in order to do this you should open the back cover of your tv then pull out the mother board of your tv but be very careful for the other wires connector may accidentally unplug you should remember the proper location of the connectors or use some pen to mark the connectors. Note that before removing the back cover of your tv you should unplug it first,Feel free to send feed back best regards.

Hi
Get the set to reset fist and see whether it helps you. To reset it do the folloing:
1 Press POWER to turn on the TV
2 Hold down RESET on the remote control.

3 Press TV POWER on the TV. (The TV will turn itself off, then back
on.)
4 Release RESET.
If this process does not solve the proble of your TV, its memory IC has damaged. Memory IC is one which holds the data we enter to the TV set, and the processed is stored. It is a nn volatile memory [the memory stored in it won't get lost even power is switeced OFF]; which holds all the data in. The data stored in it will retrive to main system processing IC each time we switch ON the TV set. This is an eight terminal IC, very samll one indeed, can be located very near to the main system control IC, at system control section. It can be repalced. This IC can be bought from most of the electronic spare part shops at your town. It is very cheap to buy. Even though it is very small and cheap one, its function in TV circuit is great. Almost all the functions data is stored in it each time we operate the system. It will have a specific number printed on it, and should be noted when buy a new one. Insist on that number, substitutions or an other number won't even switch ON your TV. OK.