The internet says try another cable or defective or press the switch on the side for a long time... Should be a protection for the 🔋 maybe you are connecting something that draws too much... Try it out and otherwise hello defective... Never had the problem with the product and have almost all sizes from the manufacturer

Some suggest to press and hold the button for 5 to 20 seconds to reset it, but I haven’t personally tried.

Flip the USB C cable and reinsert.

The charger flashes with 188, i recognize this is usually a symbol for power bank malfunction. How can i reset my power bank?

I face this randomly, or when the battery is too cold or hot. Usually by letting it rest, and trying different chargers (some from legacy USB, some from USB-C) it usually ends up working.
Haven’t checked for this brand, but usually there is no so-called reset.