I had a negative experience that turned out to have a positive ending. Sharing this experience may hopefully help someone else. A Synology Diskstation DS1812+ NAS has served well for several years, until one day it was found turned off. I pressed the power button in an attempt to turn it back on as there was no prior indication of any problems. The system did not power up. I thought that the issue was with the power supply. Fortunately, I had access to the expansion unit the was attached to the NAS. The Synology DX513 has the same power supply. I took the power supply out of the DX513 and installed it into the DS1812+. This did not resolve anything.
Now there is reason for concern. With no motherboard to be found, the next step is to look for another DS1812+ or higher system. The goal is to get the data back. After a couple of hours searching in the usual venues, such as eBay, Amazon, Craigslist and others I was unable to locate a reasonably priced NAS. I took to OfferUp. After a couple of minutes, I located a DS1813+ listed only two hours before. Within two hours, I had my hands on the DS1813+ with disk trays. I felt that was acceptable as the DS1812+ looked the same to me. I didn't do enough research. The trays of the DS1812+ do NOT fit the DS1813+. The DS1812+ uses a D5 tray. The DS1813+ uses a D6 tray.
The next step was to search for D6 trays. At around $45 each for 8 trays this is not an option. Finally, located trays for around $11 each on Amazon. I got lucky, after a day, the seller sold out. A week later, the trays arrived. I transferred the disks from the D5 trays to the D6 trays. Crossed by fingers, and turned on the DS1813+. Not only did it power on as expected, I used the Synology Assistant to locate it. On the web based screen, I was prompted with a comforting screen that indicated that the original disks (inserted in the same order as the DS1812+) from the DS1812+ can be migrated to the DS1813+ would I like to continue? The response was yes of course, then I was prompted with a DSM update - again another yes. Ten minutes later I had compete access to all the data, nothing lost. The username and password was correct. All the settings unchanged. The only thing that I had to change was the IP address.
The DS1812+ was the gift that kept giving. I salvaged the memory from it and upgraded the DS1813+ with an additional 2GB. I am saving the power supply as it is expensive at around $175. It will make for a good backup power supply. The D5 drive trays can also bring in as much as $45 each. These can be sold off to help recoup some of the added expense of purchasing a used DS1813+ plus 8 drive trays.