No you checked the battery after you got the drop off and blew the air out of your tank?
Before you gas up the gun again make sure you set everything back to stock and pull the bolt kit and make sure everything is nicely lubed. That'll solve 85% of any issues you might have and I rarely trust a gun out of the box to be greased up right.
Also New Designz makes an on/off purge that works great for the mini that'll let you degass the gun without taking the tank off or take the tank off.
You probably shredded your tank o-ring when you tried to unscrew it from the mini reg/asa causing it to blow leak all the air out. The orings shred pretty easily when you try and unscrew a tank under pressure. Another way is to dryfire the gun as you remove the tank to bleed off the excess pressure but I'd recommend the New Designz.