Probably the sensor is damaged and time to replace the scales unless it is still under the manufacturers warranty, in which case, return it for service.
O-ld is 'overload'. There are some fixes here. The first thing I would do is remove the battery and leave it overnight. Replace the batteries with new ones. If you think it may be possible that you are overloading the scale, put a bag of sugar or flour on them to test.https://www.google.com/search?q=Salter+bathroom+scales+0-ld+code..
Either you are trying to weigh something that is too heavy or the damage has already been done and the sensor has been damaged with excess weight. I bought a set just recently from ASDA (Wallmart) and they cost less than £10.
I went to the Salter website and I could not find that model number.
Salter Disc Electronic Digital Kitchen Scales White
However, looking at the other models they had there should be a door on the bottom of the scale. It looks like a release tab that you push in then lift up on. Give that a try.
Remove all batteries from the back of your scale. Leave the scale without its batteries for at least 10 minutes. Reinsert the batteries. Check that the batteries have the correct polarity and are firmly in place. Place your scale on a flat, even surface without carpet. Press the center of the scale with one hand to wake it up. The scale will calibrate and display a series of dashes. "0.0" will appear on the screen. Press on the center of the scale.
