Just throwing this repair out there. I've been suffering from released PLA prints for a month or so. I began to notice when the PLA prints release, the bed is ice cold. The problem grew over time and eventually the bed refused to heat up as of this evening.
While checking the heated bed terminals, I noticed the bed resistance was overload.. even when directly probing the terminals. As there was no damaged traces the issue must of been the solder joints on the SMD wire connector. I unscrewed the connector and gently wiggled it... however all of the joints were visibly in place and not mobile.
Eventually I screwed the terminal back down and added some solder to reflow them. Luckily the issue disappeared after that and i'm printing again. I'm guessing there was some micro-fracture in the screw header solder joint. Glad I didn't have to buy a new bed... but a little concerning that the issue was not obvious and required a lot of assumptions.
Just throwing this out there in-case anyone else runs into it and is a few clicks from purchasing a new heated bed :-)