This machine boot immediately measure to the motherboard power supply board STB5.2V, 12V, 5.3 volt power supply were normal, and then automatically shut down in the standby state, so suspected motherboard led to the failure to protect the shutdown, because there is no substitution of the model with the motherboard, motherboard 37R81BA substitution, but to change up after a open machine on the protection of the shutdown, when pulled out between the motherboard and the screen cable machine normal boot, put a piece of motherboards replaced with, everything is normal.