Chosen Solution
After replacing the faulty speakers of my MBP in-line with the iFixit guide, the device stopped detecting the battery. At login, the battery icon shows 0% for a couple of seconds, then shows an “X” icon. Also, System Report does not identify the battery. I have tried removing and re-connecting the battery, and both SMC and NVRAM.PRAM were reset, but to no avail. The laptop works fine with the power cord, sometimes slightly laggy. All was working fine prior to the speakers replacement. Any help would be greatly appreciated. Thank you.
I fear the battery cable got damaged during your repair as CoconutBattery will react this way when it polls SMC and can’t get any data. Remember your SMC data was lost when you disconnected the battery for a length of time. Time for a fresh battery MacBook Pro 13" Retina (Late 2012-Early 2013) Battery and here’s the guide MacBook Pro 13" Retina Display Late 2012 Battery Replacement
