Here are a few main reasons：
(1)The environment monitoring unit (EMU) is faulty
(2)The communication serial port is damaged or the line is faulty
(3)The EMU is reset manually
And you can replace the EMU,check whether the communication serial port is damaged and whether the line is faulty
to deal with it. You can check in thunder-link.com for more information about Huawei MA5800-X7