Sanyo DS31520 went dead (by 2 users)

If still under warranty or if you have no electronic repair experience you should take the set back to the shop or to a repair person. Some of the solutions described below can be dangerous, TV's are very hazardous to service. Even when plugged out, TV's can store very high voltages.

Squealing noise is from the power supply teling you that there is an
overload condiction. The overload is shifting the operational frequency of the power supply into upper audio hearing range. Check the diodes and caps in the supply circuit and the active components in the deflection circuit. also resolder the LOPT, h-output, h-driver, and h-driver transformer.

Good luck