Zie hier reply van synology
Seems like the mainboard is fine.
https://www.synology.com/knowledgebase/DSM/tutorial/General/Why_am_I_unable_to_install_my_Synology_NAS_and_why_is_my_power_LED_is_flashing_constantlyIf the POWER LED is blinking when DiskStation boots up without HDD over 10 minutes or only blinking for a few seconds, then the motherboard is defective, please kindly contact your local reseller for RMA service if the warranty is still valid.
Please kindly confirm your system status displayed in Synology Assistant again. There are three common statuses.
1. Ready: You can directly click [Connect] in Synology Assistant to login DSM WebUI to manage it.
2. Configuration lost / Migratable: You can proceed with DSM installation to get a fresh system without losing data.
3. Not installed: Pay attention to any RED TEXT like "Note: all data in the disk will be deleted during setup procedures." Please abort the installation if this text is being displayed in the Synology Assistant, otherwise your data will be erased. If no red text appears during the setup procedure, please kindly proceed to reinstall the system firmware to revive your DS.
If Synology Assistant cannot find your DiskStation, please try the following tips with or without the disks:
1. Temporarily remove your Firewall & Antivirus software on the computer.
2. Try to connect your computer and DiskStation directly with an ethernet cable (no router, hub or switch sits in between). Set the computer's IP to DHCP and try again.
3. Try with another computer.
4. Change ethernet cable to rule out faulty or degraded cables.
We also recommend you check the hard disks. You may take out the HDDs and connect them to your desktop PC. Then, run the manufacturer's diagnostic tools (see below) to confirm the health status of the disks. Change defective HDs if there is any.
[WD HDD: Lifeguard]
http://download.wdc.com/windlg/WinDlg_124.zip[Seagate HDD: Seatool]
http://www.seagate.com/www/en-us/support/downloads/seatoolsIf all disks are fine and you are eager to retrieve your data, please connect all your HDDs to a desktop computer and perform the actions listed in this FAQ:
http://www.synology.com/support/faq/579If Synology Assistant can find your DiskStation, please prepare another healthy spare disk, and try to insert this disk in either slot of your DiskStation to install DSM. See if you can complete the DSM installation. If the installation still fails, your Synology product may be defective. Please contact your local Synology reseller for RMA service if the warranty is still valid.
If you were using volumes with data protection (i.e. RAID1/5/6, which allows 1 or 2 failing disks), you can install DSM on a spare empty disk and then insert the remaining hard disks to read the data. (Please be advised that this is still risky. If one more hard disk fails during this procedure, then your data may be lost). Here are the steps:
1) Power off and remove all hard disks
2) Insert a spare empty hard disk in Slot 1
3) Power on and install DSM normally
4) Do not create any volumes. Power off DiskStation once DSM is installed successfully.
5) Insert the remaining old hard disks while keeping new spare disk in slot 1. (1 of your old hard disks may be left out.)
6) Power on DiskStation
Once the data in the old disks can be read, you should back them up to another place asap.
Or, you can go to Storage Manager and repair the system partition on the old hard disks. When it's done, you can remove the spare disk, install the original disk, and repair the system partition on the original disk. By doing this, your previous system configurations (user account, user privilege, application settings, etc.) will be erased, but the data in the shared folders will still be there.