My family is renovating an apartment and someone thought there was mold inside some drywall that showed water stains from when there was a leak in upstairs apartment.
This person prepared a Borax water solution using 20 Mule Team Borax (supersaturated as there was still powder at the bottom after vigorous mixing), gouged some holes in the wall and sprayed the solution into the wall. Their plan was to kill the mold inside the wall and plaster over the gouges so as to save money by not hiring a mold-removal specialist and avoid replacing the drywall.
I am skeptical of this plan and turn to this community to ask:
Does this plan have any merit?
How can I tell if there really is mold in the wall?
How can I tell if the mold is all dead after the Borax solution was sprayed into the wall?
Will paint and plaster be enough to cover up any surviving mold and keep it contained in the dry wall?