Changed the battery, now it will not charge & wifi not working

Go back over your reassembly - you've munged something up.

Many times when this happens the DIYer thought they had a good connection when it only "looked" or "seemed" connected. Make sure the card and antennas are completely and properly connected (snapped in). Same with the battery.

Some batteries have been known to go bad right out of the box, especially cheap Chinese knockoffs. If your old battery charged put it back in and see if the fault is the new one.

If this answer is acceptable please remember to return and mark it.