unfortunately thermal imaging 'sees' the temperature of the first non-transparent surfaces in its field of view so the engineers will need to come up with some gadget that's more intimate with the battery cargo that can get the "it's getting hot in here" message to the crew.
Without that hydraulic injector any heat alarm might not buy much more time, though. My gut feel is that by the time any practical device notices the temperature rise of a sizeable mass of batteries, the reaction is well established. OTOH, if there's a suitable flat surface nearby an extra minute's warning is no doubt praise-worthy.