removing vinyl pool paint from old pool

Inherited a now 35 yr old pool, which had always had vinyl paint used. Pool has sustained numerous cracks over the years due to settling common in New Mexico, and additional repairs are needed.
Only local pool service strongly said not to sandblast due to concerns re: structure, and all vinyl paint we were told must be removed before we can repair/redo with epoxy, so I have been using a 7 in. angle grinder and a 3100 psi pressure washer. film Not fun, and now that most is removed, there is still a thin film of paint in many areas.
Plan has been to use a rubberized product (sani-tred), their proprietary hydraulic cement, but they say 'all previous surface materials must be removed to insure penetration of our product into sub-surface'. I plan on following with epoxy.
Finally! Does anyone have any thoughts on how deep I have to drill? Would muriatic acid, left on for several minutes be a possible solution? Even if down to bare concrete that would be OK.
Many thanks for suggestions...

I'm fresh out of ideas: rubber based pool paint is a PITA to remove. There's a specialized grinder I've used (and I'd even love to sell it to you, since I'll likely never use it again), but it would be much harder on the underlying structure than sand blasting.

Muriatic acid will NOT remove the paint, but it will damage what is apparently a weak concrete base.

Honestly, if the pool's that fragile, you probably should either (a) do a structural overhaul (ie, rebuild for $$$$) or (b) repaint with rubber.

Too many hours into removal to quit now, so back to the old pressure washer after work. Was just hoping there was 'an easier, softer way', I had missed! Besides, I needed to identify all possible leaks, and feel good about that. Hopefully, pics of a great looking pool will be in near future.

Good luck!