User manual Weighmax L396 - RTO Weighmax W-L396 Body Fat Scale

Question edited for clarity and add maker.

The most likely reason is it needs new batteries. The secondary reason would be bad connection inside. A final answer is putting it on a surface that is not flat and stable coupled with a non-distinct switch on.

https://www.google.com/search?q=WeighMax+W-EX650C+reads+ERR

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Hello, Joanne -

WeighMax manufactures more than one model of bathroom scale. See:
http://www.weighmax.com/products/bathroom-scales-1.html

Not all the WeighMax bathroom scales take the same kind of battery. If your scale is one of them listed on the web page cited above, click or tap on the link for the information on the scale and look for the information on Power to find out the kind of batteries needed.

I do not find any instructions for where to find the battery compartment on any WeighMax bathroom scale. Therefore, I suggest you contact WeighMax Technical Support and ask. You will probably need to provide the model number of your bathroom scale. This is the link to the WeighMax Contact Us web page:
http://www.weighmax.com/contacts

Best wishes.

are you sure the batteries are good. double check it again with known good batteries.

Recalibrate. If that does not take, then there is an issue with the scale. Try installing a new battery since a bad or weak one often results in erroneous readings.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.wikihow.com/Calibrate-a-Digital-Pocket-Scale&ved=0ahUKEwjfqdn1krnTAhWEyoMKHbp5DbEQFggdMAE&usg=AFQjCNG8KZzRCEodoYOpe-rkiLg2QYNJKg&sig2=bI__GiNbQNFBTTEzVQTn_A

I had mine set to ozs for over a year and then it changed to kg. Couldn't reset it by hitting the button, so I removed the battery and then put it back in. It reset it to ozs.

This scale perfectly fits my needs. It takes up very little space on a side table, and has held up great weighing the 5-10 packages I mail per week. I have found it to be perfectly accurate and would recommend it to someone else planning on using a scale with the same frequency as me!