The phone crashed and I could not get it to turn back on, or get any buttons to respond. I managed to re-flash the firmware with SP Flash Tool. The phone now boots to Android, but there is now a "NOT VERIFY" message on the home-screen and I can't use my sim card. The sim card works in another phone.
Firmware version: BV6100_EEA_E937_V1.0_20190926V11