S.M.A.R.T. diag failed

It’s only been about 2 weeks, since recieving and installing a New SanDisk Ultra 3D NAND 2TB Internal SSD - SATA III 6 Gb/s, 2.5"/7mm - SDSSDH3-2T00-G25,  and I am already about to receive a replacement drive for this one, because it is only detected sometimes and is my main drive. But, I’m just wondering what “S.M.A.R.T. diagnostic test failed,” means? When the drive boots properly and I attempt to run either the short or long test, I get the same message, eventhough it shows all check marks on the dashboard display screen?