[Q] Xperia M Dual (C2004) totally hopeless situation.Please help! topic

Well Guys firstly my phone state:
1) Phone State:
*Volume down button doesn't work
*I can't boot into fastboot mode (may be because of above vol dwn button problem)
*My phone boots defaulty (and only) into safe mode
Hence, I can use only system apps.
2) WORK-AROUND :
I worked around this last week by rooting phone through Flashtool root section. Then I used adb to make all installed apps from playstore as system apps ( using adb shell su ..then shifting all apps to system/apps and then chmod to 644)
...and bingo all was fine untill I decided to unlock my boot-loader for future use...flashing custom OS etc ( I have no understanding of all these terms ..ROMs etc..Im quite a noob) :rolleyes:

ok so here's the start of my bad story :
I unlocked the bootloader using Flashtool....as my phone doesn't boot into fastboot mode by using hardware keys ..i used app "quikboot" which I had made a system app as said above....I booted in to "fastboot" mode using it ... then unlocked the bootloader ....and Then the phone went in bootloop .. I learn't that we need to flash stock ROM(for me ROM = mobile OS) after unlocking bootloader..so then I dowlaoded an older version of generic sony xperia M ftf file from xda...
Before flashing it I relocked the unlocked bootloader :eek:
I updated the OS to latest official. Due to the hardware problem the phone again boots into safe mode only for the newly flashed OS too

I tried to redo the "2) WORK-AROUND " section steps again:
When I try to " adb shell su " I get "su not found ..why does this happen ( I suspect because of phone not being rooted)..so I tried to rppt again using flashtoolas above..but this time while using towelroot phone reboots ( and hence the root fails) and hence I cant make those apps as system apps

So my phones up again but it locked, not rooted and I cant used any apps except the default Sony system apps(not even whatsapp gasp :( )

So I believe my only way out is to make installed apps system apps...for it that I somehow need to gain "adb shell su" working....Please suggest any alternative way around I may have ..
I really dont wanna change my phone ..its hardly been over a year only :rolleyes: