Update...downgrade...rooting...recovery flashing: I cannot do anything

I cannot do anything on my P8 lite single sim ALE-L21...update...downgrade...rooting: the smartphone goes in bootloop...the only firmware that works on my smartphone is the B203, if I try to flash (also from fastboot) any other firmware (single sim or dual sim, old or new), the smartphone goes bootloop and I am to flash from fastboot boot, recovery, cust and system firmware b203...only in this way the smartphone begins to work...if i try to root, the smartphone goes bootloop...though if I try to flash custom recovery, the smartphone goes bootloop...I tried all but the result is always the same...what is my error? :confused: Please help me :rolleyes: