Download
DriveDX...there is a free trial (or another App like it, but I mention this one as I have personal experience with it.) It will pull the SMART data and test the drive to help determine if it has failed or if it is failing. If you have really important data on the drive, you can use some software apps on your own to try to recover the data, or send it to a data recovery specialists. Unfortunately, professional data recovery is expensive, not always successful, and usually not included in the warranty with consumer drives. If you want to have the data professionally recovered, then it is worth leaving the drive powered off and not attempting any further action on your own, in my opinion.
If the return process is through the vendor rather than the maker, might be worth purchasing something other than Seagate as the replacement. I've personally had very inconsistent and sometimes very frustrating experiences, where as with other's I've had far more consistent and reliable experiences.
Further, in the future, it may be worth keeping at least two copies of your files, because every single hard drive will eventually fail, and predicting when it will fail is often difficult (SMART helps warn you when a drive is beginning to fail in many, but not all, cases, but both HDDs and SSDs can fail catastrophically without the slightest warning.) A RAID1 is a basic setup that would mirror the same data on two separate drives (or, alternatively, you could just manually save the files twice (to two separate physical hard drives.) So, if one drive were to fail, you would have a secondary copy of the same files, and would be able to replace the failed drive without risking data loss.