Do I have to start all over again or can 2nd or more coats will fix the issue?

Project: Refinishing fiberglass door (exterior) with open grain. Looks like oak grain, but I am not sure it’s a veneer or a faux grain.

Stain: Water Based pigment dye stain (for exterior) Stain is fast drying and low odor.


Top Coat: Water based base coat sealer and Poly.


Process followed: Scrubbed out the old finish using degreaser and water. Let the surface dry for day or two. Tested the stain, result was blotchy. Contacted the paint manufacture and they suggested to do a coat of epoxy as base coat for fiberglass door. Since it was a two part product, very difficult to work with a brush or a roller, and possibly would have filled the grain. I did not use the suggestion. I had no option but to get solvent based primer. Store guy gave me wall primer instead of wood primer. Noob me, bought the primer.

Here is process I followed after priming the surface…

1. Applied primer with a roller and let it sit for 48 hrs or so before sanding it with 220 grit sandpaper. Surface was smooth to touch and felt dry.
   
   
2. Mixed the stain in 9:1 ratio of stain to water to prevent stain from drying quickly. And since this was very first coat, I wanted it to be on lighter side.
   
3. Applied the stain on a smooth vertical door surface and stain was a bit runny. Since this is very first time I was applying stain in my life, I panicked a bit..
   
4. After stain application, a few moments later, stain sweated at certain places. I did wipe off as much as I could but inexperienced me, walked away thinking stain would self level itself because it’s a water based stain anyways.
   
   
   

Here are results, this is same door, but looks very different due to light. The first image is dried stain sweat and same door, but under diffrent lights.
Imgur: The magic of the Internet

Now my questions are…


• Did I make a mistake of sanding the door with 220 instead of 180 or 150?
• Can subsequent coats fix the stain unevenness or do I have to start all over again?

Wouldn't worry about grade of sandpaper
Confused re primer. If it's fibreglass, why would you want wood primer?

I would expect it to be very difficult to reproduce the original finish. Probably moulded in, if it is fibreglass.
Never heard of a fibreglass door tbh.
Maybe a group local to you would have a better idea.
(assuming your location is India, thats a long way from here.)