not sure if it's watchdog.
Here's the easiest way to tell. boot with init=/bin/sh
and, once you get the shell prompt, just let it sit there.
At that point, ints are enabled, and if there's something bad going on you need to control, you'll know it in about 15 seconds.
I had a vendor do this to me once: they changed the board and connected (on the board) and started enabling a watchdog and did not tell me -- one week before an exhibit. I had a sleepless weekend.
Of course, the part # did not change -- they never do ...
ron