What happened to the smartphone and how to fix it?

Question

Android

Prestigio Muze X5 LTE, passed out during the update by air. When you turn it on, it constantly boots into recovery. The system does not boot at all. When trying to flash through the recovery, it always writes an error: signature verification failed...

Answer 1

It looks like a killed secure boot process , or try first unlocking the bootloader, and then try to sew. Or, if it doesn't help, install TWRP and cast from it.
It is advisable to find out before all the manipulations how not to kill NVRAM on a specific device, all the unique addresses of modems, WIFI and BlueTooth adapters are stored there, because you have spreadtrum right away and I won’t tell you, usually phones on MTK and Qualcomm are in repairs

Answer 2

Obviously, during the update process, a failure occurred and the firmware flew. You are sewing some other one that is not supported, try another firmware.