course of events:
1) original FW rooted with bin4ry.v32
2) 14.2.A.0.290 rooted with NUT's method
3) 14.3.A.0.757 updated and rooted also with NUT's method; tried to do Advance Wipe in TWRP (with everything except for Ext. SD) but had 'failed' error so ended up with just a 'general' data wipe, went OK. Then flashed the 14.3.A.0.757 FW ok (from Ext. SD). Using flashtool to flash the stripped 14.3.A.0.757.ftf, went OK. booted up the phone with .757 no problem, however noticed that freshly installed apps were some how already configured and setup even though I have not set anything yet. I figured maybe it loaded up the data from .290 hence, the data wipe may not be done properly.
4) 14.3.A.0.757 again to see if the issue with the apps will rectify, however, still getting 'failed' error with TWRP Advance Wipe. I ended up 'format' data and tried TWRP advance wipe......again, 'failed' error! Tried to deselect USB-OTG, surprisingly Advance wipe was 'successful'. Then flashed with 14.3.A.0.757 flashable.zip again, this time it flashed pretty fast. so I proceed with flashtool, went well. rebooted and got stuck at Sony Logo. COULD NOT get back into TWRP to reflash.....ended up having to reflash 14.3.A.0.757 using Sony's Update Service app (SUS). Everything is ok, phone is working fine. However, I cannot go into recovery mode to flash with TWRP to root anymore. I noticed that when I press power, it vibrates once......Sony Logo.....Xperia logo and wipe screen. It doesn't vibrate twice anymore when the Sony logo comes up.
Thank you and sorry for the long thread. Just want to be as precise as I can.