Most common cause is a firmware level issue. SSDs operate like hard drive when they 'boot'. I am referring the drive itself 'booting', so controller powering on and attempting to load it's firmware from the NAND (or in case of a spinning drive from the platters).
Firmware should be taken in broad sense, so not just code but also for example the 'translator' or FTL. In turn the failure to load firmware can be due to for example improper shutdown or NAND degradation.
To recover the data one would need access to the firmware. Pro grade data recovery tools like PC3000 can try accessing the firmware by booting the drive in factory-mode and by using a custom loader. They can then attempt to for example generate a new virtual translator.
Think of it as a logical file recovery tool rebuilding a virtual file system and MFT to allow recovery of lost files from a corrupt NTFS drive.
Problem with the Pro grade tools is that they're expensive and they support only a limited amount of SSD models. The more obscure the model, the less chance it's supported, and I fear this Maxio controller isn't. A lab may still be able to recover the data but the odds aren't great.
![enter image description here](https://cdn.statically.io/img/i.sstatic.net/AJdjuUM8.png)
DIY level there isn't much you can do. IF the issue is for example at FTL level just powering on the drive and granting it idle time occasionally helps. In case of SATA you could for example power up the drive without data cable and let it sit for a few hours. I've seen cases reported where it needed over-night or over-weekend to eventually come to life. The idle time essentially allows for the SSD to fix itself (think of it as a chkdsk on firmware level).
For specific controllers DIY type fixes can be found on Chinese and Russian forums (SM2258XT for example).