Hello - Welcome to the NGA Adenium forum
Am afraid it is too far gone
But you can test to make sure ....pinch the caudex (the thickened "trunk" portion) at the soil line .....does the caudex ("trunk") collapse in on it self ?? (if yes, plant is probably gone)
a few other tests .... spread out a newspaper....then pull the entire plant from the pot ....knock off as much as potting media as possible .....are the roots firm ? (if yes there is hope)
is there a slimy mess around and in the roots ? (if yes, plant is probably gone)
have you noticed fruit flies or fungus gnats lately ? (a sign the plant has rot)