Chosen Solution

OK, I plan to review previous IFixIt answers to this most basic question, but if my iFixIt replace battery can’t resolve issue it’ll be a bummer.

Michael Russo you are using future tense. You replaced the battery already? “ if my iFixit replace battery can’t resolve issue” requires you to let us know what the issue is.  If your current battery is not holding a charge, then it is always prudent to replace it. Once replaced you can do some further troubleshooting. The battery is the only part that “holds a charge”. It either does or doesn’t.  Not holding a charge is different then drawing a charge which may deplete the battery. It is important to make that distinction