My moms car has no lights or radio and wont even turn over. Neighbor put in a new battery

No battery power immediately following battery replacement is commonly the result of reversed battery terminal polarity .. The cables were inadvertently touched or hooked up to the *wrong* battery post .. .. This will cause the main battery fuse to fail resulting no battery power .. Unfortunately - this fuse isn't the same as one of the other smaller fuses that can easily be replaced ... Hands-on assistance from *qualified personnel* will more than likely be needed.