ok, if you have some time, track down the error.
1. set your mod to the following watts:
-1
-5
-10
-25
and leave 30seconds between each setting (or 60 if the mod gets hot).
2. and for each of those, write down:
- what your mod says about the coil resistance, and if it matches what the coil should have
- the voltage, and if your mod supports it,
the amperage when you press the fire button (press for 3 seconds).
- if the temperature of the mod/tank scales with the dialed in watts (ideally, it shouldn't produce any considerable heat at 1,5,10).
3. do the above with at least 2 different atomizers. doesn't matter that the coils aren't the same. this is to illuminate whether the mod has an internal problem with the power it puts out, or if the problem is located above the 510 thread. and please do check if the mod switches to 0.00ohm when you unscrew the atomizer.
oh btw:
A) you said you bought new batteries and still have the problem. just to rule out this potential source of the problem: are the batteries genuine/coming from a reputable seller? do they get hot when you use them in other devices, or when you charge them?