Bed Heating Failed, Printer Halted, Please Reset A couple of weeks ago I have successfully built a 3D Printer and Printed an XYZ Calibration Cube with ABS material at bed temperature 80 °C.
Next Day I tried bed heating at bed temperature 80 °C,

Screen is blank

and it's not heating at all and showing Following error.

Bed Heating Failed
Printer Halted
Please Reset

Specification board
I use a RAMPS 1.4 running Marlin 1.1.X
Troubleshooting
I searched on Google and tried possible solutions but they are not working.

I changed the thermistor and nothing happened, the old thermistor is also showing the same temperature.
I connected 12V Supply Positive to SMPS (Switched-Mode Power Supply) and Negative to RAMPS 1.4 and not working
I checked the Voltage at heat bed it's showing zero in spite connecting to SMPS

Please let me know how can I fix the problem?
Check that your heated bed is still working: 


Measure the resistance of your heated bed. It depends an the power
rating of the bed, but 12V beds usually have values &lt;3 Ohms. That's
hard to measure for cheap multimeters, but you just need to check
that it's not MOhms which would indicate a broken heated bed.
Your heated bed could also have a short. That's hard to measure, as &lt;3Ohms are already 'almost a short'. You'll only notice because your
bed will not get warm, but the wires, connectors and elements on the
RAMPS will get even hotter. Marlin should detect this and switch off
after a few seconds.
Check your thermistor. Seems you already did that.
Check your RAMPS by measuring the voltage on the bed connector while setting the bed to heat up. You should see 12V, at least in the
frist few seconds.