Spark 40 cuts in and out every few minutes

[krapS40]

I am a fairly new user but had this Spark 40 for a couple of years. Haven't used it in any extreme way and pleased with the sound. Recently, it has started to cut off suddenly, stay off for a few minutes, and then come back on. It doesn't appear that the Bluetooth is involved in the connection issue because Bluetooth from my phone works in OTHER Bluetooth devices when the cut off occurs. <Also forgot to include that directly corded guitar input ALSO cuts off at the same time when the Spark 40 does.> Headphone connection also cuts off and comes back on same as the connected speakers in the Spark 40 so maybe its global and not just the amplification section (also pre-amp).

If I shut it off for a minute or two, then turn back on, it works for a while, then cuts out again. Usually, if I leave it on, about 5 minutes pass and then it comes back on for awhile, maybe another 5 minutes then it happens again. My past experience with devices tells me that perhaps some part of the circuit gets to a sufficient temperature, shuts off until a minimum threshold temp is reached, then heats again to a max temp in a cycle. Anyone seen this behavior and what to do about it?