Why is my Smok X-Priv Baby Mod not turning on?

My 5 month old Smok X-Priv Baby Mod has been sitting in my room for like 2 months straight not charging so it doesnt mess up the battery, i recently charged it and it got to 100 percent so i unplugged it but it doesnt turn on, ive looked on every website and got the same answers such as software update or stealth mode, i can guarantee its neither, because there is no sofware or firmware update for the mod on there website and i have tried many times to power on and take off stealth mode, nothing works. i am able to press the button on the bottom next to the port that resets it but only shows the SMOK starting screen and wont power on after that. Everytime i charge it it doesnt do anything but stay at 100 or go up to 100 and when i unplug charger it stays at the screen for like 5 minutes unless i hold the power button and down or up button for 10 seconds but will not go to starting screen help would be GREATLY aprreciated!