Aquabot pool robot stuck in place by the main drain cover caused a pin hole in the vinyl liner 6 inches from main drain. The stuck pool cleaner then sucked out the sand under the liner thru that pin hole leaving a large round 3-inch-deep by 10-inch round cavity depression in the pool sand floor into which the vinyl liner got pushed in by water pressure above. The pool water then emptied out slowly thru this liner hole down to 4.5 feet leaving 4 feet water in the hopper behind and the drained pool water infiltrated under the liner and saturated the sand under the liner making the patch impossible to place because the liner lifted up when the remaining pool water was emptied at which time the water from the sand under the liner reversed direction and then started gushing upwards from that hole back into the pool. Eventually after some replacement of the hopper water it was possible to place an underwater patch in the vinyl liner however the deformity from the missing sand in the pool bottom is still there and the liner is stretched into this hole with the patch. I was unable to push sand back to the nearby depression by opening the screws of the main drain liner anchor plate because so much water came gushing out from that opening made for access so I had no choice but to just reapply the main drain liner anchor plate screws and reseal that interface. There are no de watering lines in the hopper sand bottom. This is a kidney bean shaped pool 45 ft long X 24 ft wide X 8 ft deep vinyl liner with sand bottom and no weep de watering lines in place and the hydro static port in the main drain was found to have a plug in it. I am hoping that after patching and sealing the liner and refilling the pool when I come back months later in the spring, and empty the pool again, the ground sand will have dried out and I can open that main drain liner seal plate and stuff sand into that depression 6 inches away with my hand. Otherwise if this approach is not successful, I would need to measure-- which would be very difficult since its kidney bean shape with a shallow end and a slopped bottom into an 8 ft deep hopper end and there is no blueprint on file, built in 1969-- and install with a full crew of staff, a new liner and place new de-watering weep lines that were never built into this pool decades ago in the original build. Can someone, both expert and layman, give me feedback on other people’s experience with such a problem and how I can solve this particular problem in the simplest and easiest way possible and how other pool owners reporting this same problem solved it their way? Is there any remediation or financial assistance by the manufacturer of the robot cleaner that can be accessed.