I need the manual for thermostat model # T8131C10121 - believe it was made in 1997 - the "bat lo" display is coming on and I have replaced the batteries (even though it says they are not necessary to run it) BUT the display still shows the "bat lo" - I have done as it says - turned thermostat to OFF and put brand new batteries in. It will not let me control the temp now - Help please!