Does it have 3 buttons on the control panel? If so hold all 3 down for about 10 seconds. When "REM" appears release the buttons. According to the manual this should turn your remote back on. This is assuming you have a remote panel (Spa side controller, in house, etc.)
Again I agree with texas. Do you have a pressure side cleaner such as a Polaris? Or can you open the valve that feeds the 1" pvc and let us know what that does?
Inside your filter there are plastic pieces called laterals. If these get cracked they can allow sand through. They are just plastic so it's not hard to break them when you fill it with sand. I don't have a diagram for the intex but I'll post a photo of a hayward filter so you can visualize...
I agree with pools BUT keep in mind it would be under 350 to completely rebuild your pump. If your happy with it in general and the housing isn't cracked I would give this some serious consideration.
And they definitely make those wedding cake steps out of concrete. Agree, skip the rainbow and Polaris. Buy a robotic cleaner online, not from your builder. They aren't giving you much to work with yet. Have you seen a drawing yet?
The level of customization your looking for is going to be difficult to find in fiberglass. If you find something that happens to fit you perfectly fiberglass builds are often months quicker than concrete builds. If time isn't an issue and there isn't an enormous price difference I'd lean...
Theoretically you shouldn't leave any cleaner in your pool consistently. You will certainly go through your wear parts quicker. Robotic cleaners should be emptied after every cycle for the good of the bags and pumps. They are just like any other tools, the better you care for them the longer...