Hi guys. I am newly registered to the forum, but I frequently have used it to solve many issues in the past with great success. Thank you all for that! I have an issue with a 2 axis Bridgeport EZ Trak DX CNC that I just cannot figure out. I have searched the archives on here and am striking out. Serial # on my machine control is EZ-3558 and I believe it is a late 1990's machine. I just purchased it, and when I fired it up the first time, I got the following error:

CMOS Checksum error
CMOS Battery Failed
Defaults Loaded

After doing some research on the forums, I determined that the ST Microelectronics part #M48T86PCI (discontinued) real time clock had a dead battery. According to the first thread I read, the cross reference is Dallas Semiconductor DS12887+. I purchased one and when I went to install, I removed the old RTC and noticed that "DS12887A" was silk screened on the board. Before installing, I pulled up both data sheets for "DS12887" and "DS12887A" online and couldn't find any differences, so I installed the RTC. When I powered the machine back up, I get nothing. The monitor displays nothing. No green lights are lighting up on the board either. So, I powered everything down, and ordered a "DS12887A+" ("+" just means lead compliant according to the Digikey Rep). After installing this RTC, I get the same result. Am I doing something wrong or do I have a bigger problem? I have worked on machines before and am very careful during removal/install to protect against static discharge, etc. I am hoping someone here has had a similar problem. Any help is appreciated. Thank you in advance!!