Onkyo A/V Receiver and Sub Woofer (Towson)

Have an Onkyo HT-R391 5.
1 A/V Home Theater Receiver.
It currently does not work, but my inquiries indicate it may be an easy fix for someone more technically inclined than I am.
The power shuts off about 2 secs after powering on.
Before this started happening it was an excellent receiver which has worked well for several years.
For anyone who works on these types of units it should be reparable and functional.
Size is in description.
In addition I have the sub woofer which came with this unit.
It is the SKW-391 passive sub woofer that works great.
Size is 13-1/2"H ; 14-1/4"D ; 11-5/8" W.
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