A partial opening of Hong Kong’s scandal-hit Sha Tin-Central rail link is expected in three months as the embattled MTR Corporation will restart train tests on the signalling system.The rail operator announced it would resume dynamic train tests on the signalling system on the Tuen Ma line, a section of the link between Tai Wai and Hung Hom, from Monday night during non-traffic hours. The link connects several existing railway lines and has six interchange stations.Train tests on the Ma On Shan…