當日凌晨的非行車時間，東鐵綫順利改用新的 Trainguard MT 訊號系統，而首班「東鐵綫現代列車」亦如常開出
於 0700 時，YH0025 班車在上水站停止服務後，訊號系統未能安排列車到羅湖站調頭，列車車長重設車載電腦並由車務控制中心授權，中斷列車與行車訊號的連繫之後，便按傳統訊號燈的指引，駛離上水站
另外在約 0739 時，再有列車於上水站附近失去行車訊號，車務控制中心安排各班列車於車站月台稍作停留，以便工程人員進一步檢查系統運作情況，因而造成擠塞
至約 1605 時，訊號系統未能傳送車站職員放行列車的訊號，車站職員需要改用手號旗讓列車車長開車，各班列車再一次需要延誤開出
而在 1727 時，有列車駛到大學站附近時，連接架空電纜及車上機件的斷路器打開，之後亦進入「休眠」狀態，至車長將列車重新啟動為止。於 1806 時，另一列「東鐵綫現代列車」亦出然同樣的情況，列車最後在紅磡站停止服務
於 1900 時，一列「中期翻新列車」在旺角東站，因車門未能關上而要停止服務，而在行車時間結束前的 0009 時，亦有列車於大埔墟站因機件故障，而要停止服務
由於上述的情況，都未有於 2016 至 2020 年多種試車的情況發生，工程人員正與訊號系統承建商德國「西門子」，以及列車生產商韓國「現代樂鐵」跟進有關的情況
一旦訊號系統全面失靈的話，港鐵公司亦可以安排於 2 月 6 日（星期六）起的兩星期內，改用原有系統以及舊有車廂
During non-traffic hours that day, East Rail Line adopted the new Trainguard MT signalling system successfully and the first East Rail Line Rotem Train was dispatched
However, at 0700 hours, the signalling system was unable to let service YH0025 to depart for Lo Wu after terminating at Sheung Shui. The train captain eventually reset onboard computers and cut out all linkages between the train and the signalling system upon authorisation by the Operations Control Centre and used traditional signal lights’ guidance to leave Sheung Shui
At 0739 hours, trains were unable to receive proceed signal at Sheung Shui. Congestions began when the Operations Control Centre arranged all services to be held at platforms for engineers to further inspect the status of the signalling system
At 1605 hours, the signalling system was unable to relay train dispatch message made by station staff. Hand-signal flags were then used instead; services have been delayed yet again during this time
Then the circuit breakers on a train, which connected overhead power lines with components onboard, were tripped near University Station at 1727 hours. The train then went into “hibernate” mode until the train captain restarted it. The same situation occurred on another East Rail Line Rotem Train at 1806 hours, of which it was followed by a successful restart attempt. The train was then taken out of service at Hung Hom Station
At 1900 hours, a Mid-life Refurbishment Train was withdrawn at Mong Kok East when doors were unable to close properly. Another train was also taken out of service at Tai Po Market at 0009 hours, just before the end of traffic, because of a train fault
Situations like the above have never happened during the numerous train testings between 2016 and 2020. Engineers are now following up on these occurrences with the German signalling contractor Siemens and the Korean train manufacturer Hyundai Rotem
The MTR Corporation could switch back to and re-deploy the previous system and trains if the signalling system suffered total failure in the following two weeks from 6/Feb (Sat)