My battery going dead from 100 to 0 after overnight (did this twice in last week just started doin this). I went to the recovery mode to clear the cache and I noticed it showed an android with the message installing update then next figure shows ! in a yellow triangle and android on its side. Is this normal?
This is normal, correct. The Triangle with the ! means the recovery menu is waiting for a command from you.
If Recovery hasn't been booted, system updates will also update the Recovery environment. Recovery won't install the update until it is booted ito.