Before doing anything with the firmware, if I perform a factory reset, could it be solved?
I will not have problems if I perform a downgrade?
where can I see how it is done?
Factory reset will help if is Poster 2.0 loading problems until add some path to library this is specific bug on f/w v1.2.6.6.
Downgrade can cause some problems if difference between f/w version is too big, easy to be solved with factory reset after f/w downgraded.
In unlucky situation of soft brick will need to follow recovery process with f/w 1.1.0.7
http://en.egreatworld.com/comunity/index.php?threads/egreat-a5-the-instruction-to-force-to-recovery-the-firmware.385/
http://en.egreatworld.com/comunity/index.php?threads/a5bd_en_firmware_20170119_v1-1-0-7-rar-release-2017-01-19-v1-1-0-7.435/