There are at least 11 screws on the back of the TV highlighted in red that will need to be removed to get to the inside panel where the problem circuit board is located.

There are at least two different screws that you will need to differentiate. They're all Philips screwdrivers. Although, some are in holes too narrow to use a magnetic screwdriver with bits.

The ones in green, depending on which model Hisense you have, may or may not have to be removed. Some were one whole cover. Some, like the one pictured, were 3 sections.