0.1mm clearance to the surrounding metal plate with edges that dug into the battery if it expanded more than 0.1mm was enough? Did you even look at the outside analysis. 0.1mm isn't enough for normal non-battery thermal expansion. Lithium batteries swell when charging and discharging, as much as 5% and 0.1mm wasn't even close to enough.
Normal charge/discharge at thermally controlled rates would have exceeded 0.1mm. After a few cycles the metal plate's ridges would have poked holes in the battery and started bridging anode/cathode causing a runaway discharge along with a runaway thermal event. We call those runaway thermal events fires. Every competent designer familiar with Lith-ion expansion characteristics said the 0.1mm was way too small for a device that's going to be charging and discharging so frequently and so often.