Adding support for Mikrotik wAP R AC LTE6 kit

Hi,
I trying add support for Mikrotik wAP R AC LTE6 kit (RBwAPGR-5HacD2HnD&R11e-LTE6). Everything working fine, but I've problem with one thing - after few restart/power off (sometime 4, sometimes 10) device hangs. Device is not booting at all, without any messages on serial console. After reflash via tftp, device works and hangs again after few reboots.
Has anyone encountered such behavior? It works without any problems under RouterOS.