Ifb neptune dishwasher drains after a minute of taking in water

To all the real experts and DIYers, this problem has stumped all the techs at IFB and I am at my wit's end. The IFB Dishwasher, Neptune DX, not in warranty, serial number 00206433***********288 stops with an F5 error within a couple of minutes. Guys, get a cuppa coffee coz this is going to be long...

Upon selecting any cycle, it will intake water, stop a few seconds, start the circulation pump and spray water starting the cycle. But a minute later, it will drain and the machine stops with an F5 error.

1. The techs at IFB who believe in only replacing parts and repairing the machines with trial and error method started by replacing the heater-diverter assembly. Still the same.

2. They checked the drain motor and replaced it. Nope.

3. They replaced the circulation pump. Nope.

4. They replaced the flow meter.. well, the reed switch pcb on the flow meter, since the flow meter wheel is inside the entire plastic assembly.

5. They replaced the entire wire harness. Nope.

6. They checked the inlet valve solenoid. Thats ok.

7. They finally replaced the controller card. Well... whaddaya know... Nothing.

8. Spanning over a couple of months and many visits later, this trial and error method with permutations and combinations of old with new parts solved nothing. Leaving the new and old parts behind each time gave me an opportunity to check everything with a multimeter. Every old part shows the same continuity or resistances/ readings like the new part.

9. I am left with the old and some new parts, viz, the heater-diverter assembly, the flow meter assembly, the controller card, which they wouldnt take back, a hefty invoice, and a loss of confidence in IFB.

So here are my observations- I have cleaned and dried the entire dishwasher. I have scraped, checked each wire and the spade connectors, the wire harness is good. There is no leakage anywhere in the dishwasher. There is no scaling, no debris, in any pipe, anywhere. Basically, the water supply in our area is really good. The micro switch on the float which is below the dishwasher connected by 2 overflow pipes is working correctly. The micro switch on the heater assembly is working. The circulation pump, drain pumps checks out. The inlet valve solenoid is good too. The spray arms are clean, rotate good. The salt and the rinse aid dispensers are filled and their indicator lights are off. The drain pipe is hung at the correct height with proper loops. The one minute reset will start the drain motor, click the diverter with whatever it does, and stop correctly. If I open the door in the middle of anything, the machine will stop with a blinking pause

When I start any cycle - The drain motor will run for a few seconds. The inlet valve will start taking in water. I see the flow meter rotating. The inlet valve will stop after a few seconds. The circulation pump will activate and the spray arms will start rotating. This is when I see that the inlet valve has opened and it is taking water in again. The flow meter is rotating. Then in a few more seconds, the drain motor kicks in and it will drain and then the machine will stop with an F5.

Tell me anything, I'll experiment.