A: Yes. First try wiping the cache partition in recovery. If that fails, reinstall the full firmware.
Installing custom firmware updates requires some technical expertise and can potentially brick your device. If you're still interested in installing custom updates, here's a general outline: zte blade a34 firmware
A: Only if ZTE released a newer firmware for the Blade A34. You cannot flash a ROM from a different phone. A: Yes
– many contain malware. Use these official or reputable sources: zte blade a34 firmware