Firmware problems

Hi

After being advised to upgrade to the new Firmware i have found that i am getting a lot of problems, first, annoyingly my right hand gain control seems to have gained a life of its own and increases and decreases without me even touching it! But worse than that i keep losing power to the Z1 meaning the sound cuts out intermittently and then comes back again. I spoke to some tech people who advised me to upgrade my iOS to El Capitan but i found that this didn't help and in fact created even more problems so i have downgraded back to Yosemite. I have also tried resetting the PRAMs as that was another thing i was advised to do but still i am having the same problems.
Irony is when i upgraded the Firmware it said "If you do not upgrade then your Z1 may not work properly" yet upgrading seems to have caused all my problems as it worked absolutely fine before. Is there anyway i can fix this or should i just confine my Z1 to the dustbin