On certain GE top-load SmartDispense models, H2O can appear when both the detergent and fabric softener reservoirs are detected as empty. It does not automatically mean there is no water at the faucet.
Check the dispenser reservoir selection
The manufacturer documentation explains that a low level with bulk dispensing selected can prevent the cycle from starting. Check the indicators for each reservoir and whether both functions are actually enabled.
On the compatible model, temporarily disabling both dispensers using the procedure in the manual lets you check whether the cycle starts again. If it does, the issue is focused on dispensing; it is not a test of every washer component.
Refill without using a universal amount
When first putting the machine into service or after both reservoirs run completely dry, they may need the initial fill specified so the system registers a level. Use the amounts and products specified for your unit, without exceeding the marks or mixing detergent and fabric softener.
If you are washing in manual mode, confirm where and how much product to add so it does not also be added automatically afterward. If H2O continues even though the reservoirs are filled correctly, contact support with the indicators you observed.
If the display says H2O Supply, go back to the GE index to identify the platform and the water inlet guide; that message follows a different path.
Keep a photo of the levels and selected dispensing functions before changing them.