After you register your product's serial number with yours support.huawei.com account it will take about 24 hours to approve your application. After your application was approved you will get access only to recommended version of VRP which is ***.cc file.
AR109GW-L is the very new device.
Currently recommended version for AR product in 2018Q3 is V200R007, but this router comes from the stock with V200R008 and spread of this firmware is restricted. That is why you got into such difficulties.
Where are you from? Based on this info you can select nearest TAC(Technical Assistance Center).
http://e.huawei.com/en/service-hotlineBecause firmware is basic feature of a router. So you don't need to pay anything.
TAC will ask you account on support.huawei.com and then they will make online application for you to get access to V200R008 firmware.
Then you can use Xmodem to download VRP to your router but it is veryyy slow 9600 bits per second so transfer will take a while.
P.S.
Also problem might be in a RAM module. If this module is unpluggable you can clean it and it's slot and try to boot again.