The TPV56PB801 is typically a (often referred to as a "combo board" or "LIPS" board – LCD Integrated Power Supply). Its primary roles include:
If voltages are correct, the SPI Flash IC firmware is likely corrupted. You will need to desolder the IC and reprogram it using a programmer like the RT809F or CH341A. Sound Present, No Picture (Screen Flash/Black Screen) tpv56pb801 schematic diagram pdf