How to recover files from corrupted Innodisk SATADOM D150SV

After 9 years of use, this 4GB SATADOM finally broke and wiped itself to the extent that the underlying Linux partitions are no longer visible. While the device will show up as /dev/sdb, even testdisk cannot detect partitions. When choosing an Intel/PC partition, I get the errors: Partition sector doesn't have the endmark 0xAA55 When choosing EFI partition, I get the error: Bad GPT partition, invalid signature. Trying alternate GPT Bad GPT partition, invalid signature. Is there a way to recover any of the files, or preferably even mount it properly after fixing the superblock issues? Ideally I would like to extract a PostgreSQL databse. At the moment I made a backup with ddrescue, which detected 0 read errors, curiously enough. MTBF: 4 million hours Flash endurance: 100,000 program-erase cycles I suspect the flash endurance has perhaps been compromised - the warranty is curiously only for 5 years.