as it was more than a year ago, i don’t remember exactly but i think updated from my MX3 (3.7.3A) to 3.8.5 first then to 188.8.131.52，then 4.5.7.
after that by OTA to 184.108.40.206A and now 220.127.116.11A
many update procedures are required.
if you are a heavy music listener, stay at 3.7.3A forever. the sound quality was best at it even with many bugs.