flasher and warning flasher again

who can help me and knows this problem? Omega Combi 2.5 td ́95. We have built in a new battery and now there is a strange problem. Warning flashers and the flashers (in this case ignition) do not work in the state, but could be important for the warning flasher. There is no more blinking after one time. No light and no clapping. Climate, radio etc. work. I then start and drive only 100m everything goes perfectly!!!!!!!!! This stops after turning off the car about 2-3 hours a Then the same game again. When locking or opening the car (theft protection) the turn signals do what they are supposed to do. What can that be??? Maybe someone knows this game? Thank you Angelika