Lynx has a big reputation or atleast a menion here. Poor support is something to watchout for even if it may be the buyers fault. After all the buyer may have trusted him from any corner of the country. If there is simply no response, I would beware from LYNX. Atleast he could have got back with the solution.
Now coming to the problem, You should atleast see the boot screen of the motherboard if all is fine. The software stage (if any) comes next in the sequence. So incase you are not able to make it to the first screen, it may mean that wither the RAM or the motherboard is faulty. But it may be difficult to get the change incase of no response! So then you may have to live with it.