If the overhead light is flashing you might have a problem with the safety sensors on either side of the garage door near the floor. Either something is blocking their view of each other or their alignment is off or a wire to one is damaged. If the opener does not receive the right signal from the sensors it will not allow the door to close as it â€œsensesâ€ something or someone might be in the way.
In an emergency you can still close the door with the wall switch if you hold the button down continuously until the door is closed. This over-ride will only work on the wall control since that is the only control that assures the operator is in full view of the door and can confirm it is safe to close. Any opener and door have enough force behind them to seriously damage something or cause serious injuries if accidentally closed at the wrong time, so the over-ride should only be used for emergency situations and the opener should not be used otherwise until the problem is found and addressed.
If only your remotes have stopped working and the light you mention is on the wall control panel, then your opener might have a
feature designed to prevent the door opening with remotes if you are on holiday or for other reasons.
If the light you referred to is a small LED light on the overhead unit and it is flashing in a set pattern then it is likely a fault code. The links below have more information on what the faults might be or other possible problems.