I am afraid to tell you that the transmitter of Sinbad is very probably sending from the very same spot since quite some time. It's David Douglas who gave me the hint to check the activity sensor of the bird and indeed, the activity sensor is not showing any activity anymore. This means that a) the bird is dead but the transmitter is still exposed to the sun and is therefore still sending signals (and the movements we saw is just a dispersion of ARGOS errors) or b) the bird lost the transmitter and the device is lying on the ground, exposed to the sun.
I am really sorry but very obviously we will not be able to follow the spring migration of Sinbad!!!