Can't find instructions for Homedics digital scales SC-390

The HoMedics digital scale SC-300 uses a CR2032 lithium coin cell battery. This battery has a diameter of 20mm and a thickness of 3.2mm, which makes it a small, flat battery that can easily fit into the scale.

change new

Open it again and make sure the battery is in the correct angle..... I have made this mistake from time to time

look under the edge there should be a dial to turn

You have probably set your scale to kilogram and not pounds. There should be a button to set this underneath the scale or even a reset button to reset the scale to its original settings.

I just had this problem on set Salter scales (says 3309 on label on back so assume that's model no) which came up OUT2 solidly after hadn't been used for a while.
Looking on WWW this means on other scales they need to be recalibrated. There are only 2 buttons on ths model ON/Zero and 2nd is mode for grams, oz etc. Discovered by trial and error have to hold down the on button and repeatedly click the measure button as it powers up, screen says err2 press on button again and says 5000g, put 5000g weight on scales, press on button again display says CAL press on button and it at first came up with EEEE and failed but next attempt it said PASS and it all worked again. I used 2 x 1.5kg bags flour and 2 x 1Kg bags sugar to make 5kg with bit tipped out of one to make exact and checked on another set scales. So trick appears to be finding how to get your scales in to calibrate mode and what the weight it expects is.

http://personalcare.owneriq.net/manuals/mfg/homedics/homedics_scale_product_list.html

go to this address and you can download themanual for your scale. good luck.

Sounds like a warranty issue. I would try to return to place of purchase if not here is web address on manufactures site with instructions on warranty.

http://www.homedics.com/products/warranty-returns