Dear Jacob,
It is a Yantra. It has the word yantra inscribed on it.
It has :
యంత్రరాజాయ విద్మహి(sic) మహాయంత్రాయ ధీమహి శం నో యంత్రః ప్రచోదయాత్
(yaṁtrarājāya vidmahi mahāyaṁtrāya dhīmahi śaṁ nō yaṁtraḥ pracōdayāt )
అస్మిన్ తాంబ్రయంత్రసుఖం చిరం కర్తుం .... స్వాహా
(asmin tāṁbrayaṁtrasukhaṁ ciraṁ kartuṁ .... svāhā )
హీం జ్వలాయ విద్మహి (sic) మహా శూలినే ధీమహి
(hīṁ jvalāya vidmahi (sic) mahā śūlinē dhīmahi )
There is a mention of a deity called pratikriyāśūlin in the yantra.
This may indicate that the yantra is meant to counter the action of another supernatural power.
If this guess is correct, it is usually not the kind used in the pratśṭhā in a temple.
The interpretation " it is a Telugu "Saccra" (cakra) used to ward off disease and spirits of possession" should be correct.
Using yantras in the installation (pratśṭhā ) in a temple is a usual practice. But this one does not seem to be of that kind.