I'm back online, trial and error by luck..
Below chrono was roughly what i did
1.remove WU account (backup 1st)
2.remove Wazapp account (never remove/uninstall it all the while, not sure abt the rest)
3.reboot
4.register via Wazapp, fail old version
5.register via WU, connected n retrieve all unread msg from WU down till to-date, but connection still not stable
6.reboot and WU still not stable
7.after multiple times reboot finally WU stable now..
Will report back again