Accidentally Overwrite the current files

[ahming]

Dear All,

I am a newbie of NAS user. Here is my history
(1) I have TS-451 and find one of harddisk slot show error.
(2) I bought a new NAS TS-228
(3) Create a PTRR backup from TS-451 to TS-228
(4) Once the backup was completed, I took TS-451 to repair centre
(5) Repair centre informed to me they replaced the backplane of TS-451
(6) I reconfigured the TS-451 and check NO PTRR job was running in TS-451
(7) After an hour, my colleague told me the current files in TS-228 was updated
(8) Therefore, files in TS-228 were totally lose.

Questions:
Any method to recover the lost files?
Any idea why PTRR was running and overwrite the new files?