The device is crude, not modified.
Like previous Fnirsi toys, it does not measure the ESR of capacitors correctly.
It does not measure the ESR, but simply shows pre-programmed ESR values based on the capacitance of the capacitor!
Even the old original LCR-TC1 transistor testers show the correct values.
Here is a 1.5uF x 400v capacitor that should show an ESR of about 25 ohms, the old TC1 shows close to the actual 21 ohms.
And the Fnirsi toy gives a completely wrong value of 4.9 ohms.
The Fnirsi tester is not suitable for measuring the ESR of capacitors.
This 1.5uF x 400v capacitor was tested on expensive Der EE DE-5000 and RuoShui 4091C devices,
its actual ESR is approximately 30 ohms. Updating the Fnirsi firmware to the latest 1.0.5 also did not help.