I read the 2nd gen Ryzen is too new for motherboard bios . Do I need older processer to update bios ?
If a motherboard boots with a processor, then you can use that processor to update the motherboard BIOS.
Ryzen 7 1800X is a 1st generation Ryzen CPU, and should be compatible with MSI X370 Titanium starting with the original release BIOS.
Therefore, your boot difficulties are not due to incompatible parts, but some other reason.
Could you list your hardware, and explain what troubleshooting steps you have attempted thus far?
also include the motherboard's troubleshooting LED if any are lit or Motherboard Error codes.
Also do you have access to BIOS or does your screen have no video at all when you power up?
When you boot up is the CPU and GPU and Case fans running? Does the computer shut down as soon as you boot up or does it stay on?
Do you have your monitor connected to the GPU card or the Motherboard?