From the first two alert looks like Memory module on DIMM 1 is failed and CMOS battery on the motherboard is having low voltage. You can replace these two to remove those alerts. These alerts are not blocking the server to boot. You need to have hard drive storage to install operating system. As your system does not have any storage where operating system is installed it is throwing the error message of No boot device available. You need to connect Hard Drive and install OS to continue the booting of the server
Dell Precision T5500 is not booting. I have attached an image of the error message I am receiving. Also it doesn't have a hard drive on it.  How can I fix this error so I can connect it to dell for the much needed software updates and system analysis. Also I tried to run F5 diagnostic but it was getting stuck on memory after 5%. Do I need a hard drive to run the OS.  Any advice, recommendation will be much appreciated.   [IMAGE]analysis.   
Dell Precision T5500 no booting