Hello Guys,
Same problem in my Aqua 2013 S 4 grade, but my mechanic found the error and he solved EV problem just 15 mints, i really thankful to this guy, the problem was in batteries cooling fan, the cooling fan choked by dust, you can easily clean the fan by your self, no need to go any electrician or any mechanics, 90% of mechanics is suggest you to change the batteries or cells.
Check your back seats, here you can find the cooling fan, you can easily open by 4 secures and clean it, and install again, your car will be working fine in EV mode.
please check the following video tutorial
Remember in your prayers.
Junaid