Answer to "Why isn't the battry working properly?"Did you buy an OEM battery? That should be the ONLY battery you buy....one actually manufactured by Apple's supplier. Apple's OEM batteries have a safety chip in it that communicates proper functions and protections across the cells. Don't buy unknown batteries that risk damage to property and health.
Answer to "Does iMac accept 64GB of RAM?"For those saying there is no need for 64gb, you are obviously not a composer or video editor. There are many media applications that use all 32GB of ram, forcing pro users to compensate with RAID 0 or SSD arrays.