Doh. I know what that 7.9 ohms is. It’s not a miscalibration. The meter measures the ttotal resistance it sees, which includes the resistance of the protection elements. The protection elements’ resistance is subtracted back out as the final step before displaying a reading. So when you zero the meter in resistance mode it will subtract the protection element resistance from zero, resulting in -7.9 ohms. The order of operations should be changed, fixing now. Thanks