Dear customer, I understand your query. There are several aspects that we have to verify.
The first thing is to check if we can hear the characteristic sound of the relay when the indicator lights flash, it is that sound like a "TAC TAC TAC", every time the light blinks if we can not hear this sound, it is defective and it has to be replaced which is very common that happens.
If even after replacing the relay the problem continues without working the lights This worries me, because although it seems to rule out the fuse box. Remember that the legs where the network connections fit can get to overheat or simply to be damaged which in some occasions a replacement of the fuse box is required.
On the other hand If the relay is working, we should check with a tester if voltage is coming to the flashing bulbs, and evidently verify if the bulbs are burned. Although it is unlikely that all the bulbs have been burned at the same time.
If the bulbs are good and the relay is activating, the work gets a bit cumbersome. You have to check the wiring line, that is, you have to verify the wiring of the relay until the bulbs to see where it is being cut the communication. This can be due to problems of corrosion in the wiring or that has been stung at some point and it is necessary to carry out the pertinent repairs in these defective points.
I know it's a cumbersome job but electrical-related jobs of this type are always annoying, but the truth is not something of the other world or impossible to repair only that the recommendations i gave you deserve patience to be able to discover with precision the point where the defect is.