[MrSurly]

A bit of update: RevZilla to the rescue! I notified SENA and they had no trouble offering to send an RMA. There was a teensy problem, though. The. RMA wouldn't be issued until it was boxed and ready to ship, BUT....They didn't have any cameras! Some emailing lead to an OK from SENA for the replacement to come from Revzilla so I DID get a replacement PRISM. The new one promptly started glitching. After a bit of experimenting I finally figured out what was going on. Any of you who might've followed my preparations for Yellowstone may recall a connection here.
I sent the following note to SENA as a part of the repair ticket conversation:

Before this ticket is closed I would like to offer some information that may be helpful.
I believe I have discovered an explanation for the difficulty that I had and the information *might* be helpful to others.

The issue I had (the Prism 'locking up') initially occurred after only two days of operation. It was recoverable by removing the battery.
After it locked up like this a few times, it became NON-recoverable. This lead to this replacement ticket. After receiving the replacement unit it, too, locked up.
I resolved that it must be something that I am doing... however, all I had done so far was utilize the cam as a ‘dashcam’ in my truck, with a micro USB cable powering it. I recalled (eventually) that this is the very “cigarette charger, micro usb” that was supplied by SENA with OTHER SENA units (SMH10, SM10) but not supplied with the Prism.
I reminded myself that I had previously discovered while troubleshooting some SM10 issues that this particular “cigarette charger, micro usb” from SENA is NOT a 5V regulated USB power supply, but is in fact *WIRED STRAIGHT TO BATTERY VOLTAGE*. Any USB device (ostensibly a 5VDC device) would receive 13.5~14.3VDC(!) from this dangerously un-marked SENA cable.
Most usb devices such as smartphones are internally protected such that any over voltage input is blocked, i.e. a Samsung S4 will simply not charge if this plug is used.
Experience has shown that the SMH10 and the SM10 do not block the high voltage, but apparently regulate it internally and still allow their battery to charge. Well the PRISM lacks this protection. It doesn’t block the input, nor does it properly self-regulate the higher voltage. The end result is that a SENA-supplied non-spec charging cable is the cause of the PRISM dying.
Multiple tests confirm that when this ‘line-voltage’ adapter is used, the PRISM will overheat and eventually lock up. While this incompatible charging device is NOT supplied with the PRISM, it can be assumed that most PRISM buyers WILL own one of these. Using any other standard 5VDC charger lets the PRISM function without issues.
Irony: SENA supplies a non-compliant USB charging device with SOME SENA gear. This charging device has the potential to fry unprotected 5VDC devices. Fortunately for SENA, most 5VDC USB devices have internal protection circuitry to prevent damage. The first device that I found that is susceptible to this danger is actually a SENA PRISM.