Hi! I just bought my first vape which is a Sigelei Shikra with a voltage input of 6.4V to 8.4V. I bought new batteries as well LG HG2 18650 20A(flat top) 3000 mAh which has 3.6V each. There are 2 batteries inside of the vape and they both have run out of energy. Im trying to charge them with the usb cable I got with the vape but it only displays "check battery". Ive tried to change the positions of the batteries, turning them, and even cleaning them and the port, but nothing works. does anybody have some tips for the noob how to solve the problem?