Attempting to measure such things in-circuit is extremely problematic, because one’s also measuring everything else that’s connected. Without a schematic and intimate understanding of the device, such tests are more likely to seed confusion than yield useful information. Besides, those look like ballast resistors for diagnostic LEDs, which are frequently not essential to device function.
Again, without a schematic and intimate knowledge of the system that’s probably not a good idea due to risk of causing further damage.
That’s… Anomalous. Plausible explanation for a properly boomy explosion would be ignition of hydrogen that’s commonly liberated during the charging process, possibly by the arc of relay contacts. The corner of that one below looks like it might have had an experience. Sealed relays commonly have a vent nib that’s broken off after assembly in order to disperse schmoo that happens during contact arcing in the interest of prolonging contact life. Would stand to reason that there might be a bit of blowout if enough H2 got in to make things spicy.
A typical “car” battery of the flooded/sloshy type would perhaps be a questionable choice for use in an un-vented or partially-vented enclosure for such reasons. AGM type would be the better choice.
Failure to close is commonly caused by improper function of the anti-squish mechanisms that are almost universally included these days to take all the fun out of racing Grandma’s garage door. Highly plausible that there’s a bad connection, limit switch, etc. in that apparatus that’s giving issue, and that the board itself is fine.