MacBook Air Not Working After Battery Replacement

Enduser here who got a MB Air in mid 2014. All good up until now, but battery was draining quickly. Checked, and it had over 900 charge cycles. Although Apple says it should be good to 1000+ cycles, i was only getting a couple of hours of usage under best conditions.

Looking at options, it seemed relatively straightforward do a battery replacement myself.

Ordered the IceTek replacement battery for my model from Amazon. https://www.amazon.com/gp/product/B07JQQ...

It had decent reviews, and came with the necessary hex tools, as well as replacement screws. Somehow 4 of the original hex screws had come loose and were lost over time in normal use, so getting some extras was a plus as well.

All went as planned. Removed the old battery, attached the new one with the single connecter plug, and reassembled. This consisted of bolting in the new battery into the computer body with the 5 screws, and then reattaching the bottom panel with the 10 screws. New battery fits snug, and assembled with a good fit.

Went to do the first charge and mag light does not come on, amber or green. After about 30 seconds of being plugged in the computer fired up even with the lid closed, and is in the “choose user” state. (I have two users for this laptop). However, the keyboard and trackpad are non functional, even when plugged in. The battery reads 22%. The fan starts going. The power button does not turn the computer off, and the unit does not go to sleep even with the screen folded down.

If I unplug it, after two to three minutes the computer seems to shut down (or sleep) I can’t tell. If I reattach the mag plug it returns to the state above, which makes me think it’s in “sleep” mode.

At the moment i’ve attached the magsafe cord let the battery charge fully, to see if maybe it is a matter of the battery not having a sufficient enough charge. However, the fact that there is no light on the magsafe, and that it turns itself on with the cover shut is, well, freaking me out.

Any advice from those with experience most appreciated!