Console Not turning on

Started by turning on, then back off. After a few times of pressing the on button, it would work for a week or so. Then it would do the same thing, only this time it wouldn’t come back on at all. Now it is totally dead and I have a very sad little boy who can’t play his new LEGO game we got him the very same day it broke. I ordered a new internal power supply from amazon and replaced it. Did the same thing. No power. I measured the voltage coming out of the power supply while plugged into the outlet. Its reading 11.8 DC volts. Other than replacing the rf module or motherboard, I’m at a loss. Is their a replaceable fuser on the motherboard?? Any help would be appreciated.