Z,
Trying a new coil is the next step in troubleshooting your problem.
IF a NEW coil does not work, then yes, it is the
tank.
The mod should be just as it was before you washed the
tank. Normal/functional.
Pop the batteries out and back in to give it a little reset.
If your display is showing 0.0Ω with NO atomizer attached; presume no issues.
In general, any ohm reading from the device without an atomizer/
tank attached is a potentially fatal symptom and the device should be replaced. (Call your "Friend" for a refund)
Cheers
I