I was charging my ST16. It showed a charge of 77%, I then turned it off to finish the charge but when I tried to check the charge again the ST16 would not turn on. I then noticed that the screen stayed backlit after switched off
Unplug your ST16 battery for a bit, plug it back in, then let it complete the charging before attempting to power it on. Even when off, when you plug the charger in the display will blink a few times, show the charge indicator, then turn off. With the ST16 off, Just tap the display to see the charge indicator as its charging.