Hi Monika,
Old method (Case 1) is deprecated by SAP long back...... it won't work and if it- there are lots of bug in it which will result in other error and can cause trouble in later stages.
The new method (Case 2) i.e. to call the Fiori Launchpad (here, you need to call the FLP using Web Dispatcher URL; not the Gateway one). Please refer the below URL's which will help you to narrow down the issue,
On a high level,
wdisp/system_2= SID=EXT, XSSRV=https://<HANAXSHOST>:<XSPRT>,SRCSRV=*:443, SRCURL=/sap/hba/;/sap/hana
Change per your business requirement and then Run the command as below,
C:\sapwebdisp>sapwebdisp.exe pf=sapwebdisp.pfl -checkconfig
If all Good then Start the Web Dispatcher Services else check the error's in Log and or on screen.
Hope this will help.
KR,
~ Mahendra