"Random" shutdown after battery replacement

If the problem only occurs while running the laptop from the battery and not the charger, then you likely have a bad battery. Take the laptop back to Apple or the AASP so they can fix the problem under the 90 day part/repair warranty. It is extremely rare to receive a bad battery from Apple, but it does happen once in a while. It could also mean there is another underlying hardware issue with the Logic Board.

If you replaced the battery yourself, then you may need to replace it again. Keep in mind the quality of third party Lithium-ion Batteries is extremely poor even when purchased from a reputable vendor such as OWC or iFixIt which is why I will always choose an official OEM battery first whenever it is available. Unfortunately Apple will most likely not replace the battery once you've removed the original Apple battery.

Should the battery have been a 'newertech' from OWC, their method

of re-calibration is recommended. While an Apple-sourced battery is

not subject to a calibration routine. But may help recover usefulness.

Other things to check into, may include startup in Recovery to repair

the drive, by use of Disk Utility. (Or try Safe mode to see if that helps.

Let Mac run in Safe mode, 20 min. Restart 'Normal' w/o keys held..

To tell the Mac has restarted in Safe mode, you probably requires at

least one login with admin or user password; then words Safe mode

usually appear on upper right side by menu bar.

However these ideas are only as good as implementation. If the Mac

had not seen an adequate charging duration, the failure would occur.

Generally this still works, even with an older original replacement Mac

battery. Not certain of its source, as 'cycle count' may not be first one.

Mine sees use with Mid 2012 MacBook Pro, 2.5GHz dual-core, 13-inch

w/ 16GB RAM and 240GB blade-type SSD aftermarket storage/drive.

Has Mojave 10.14.6 installed; with 25% capacity used at present.

• How to Calibrate a portable Mac's Power System - NewerTech

https://www.newertech.com/batteries/power-calibration-guide/

My older Mac portables have seem only newertech batteries since

they're too old for official Apple replacements; & I've had no issues

with Calibration schemes. Even oldest info OWC shows online; for

used with vintage 10.4.11or 10.5.8. My MacBook1.1 '2006' runs 10.5.8.

[For mine, the calibration may see once or twice a year, if I'm bored.]

The SMC reset may (or not) be helpful. Consider if you'd try that; older

instructions, with less busywork associated with later hardware change:

Are better used with older, not the later Intel-based Macs. ~ Also try to

reset NVRAM, and hold buttons down through two-chime cycles; prior

to letting go of the 'four-keys held' during restart.

One of the SMC resets from adequate source, not strict to a newer hardware

regime; may be better. I've some bookmarked; not reviewed for this aspect.

• Resetting SMC (system management controller) on a Mac | lifewire

https://www.lifewire.com/reset-smc-system-management-controller-on-mac-2260840

• Reset NVRAM or PRAM on your Mac - Apple Support

https://support.apple.com/en-us/HT204063

• How to reset NVRAM, PRAM, SMC on a Mac | Macworld

https://www.macworld.com/article/224955/how-to-reset-a-macs-nvram-pram-and-smc.html

Thanks for the update. I'm glad you got it working again.