I have bricked my android phone. Is there any way to go back?
Look at MTK Droid Tools and SP Flash Tool.... 
MTK device's are virtually unbreakable ! so don't be too worried.
Try to flash the custom recovery ( clockworkmod ) and then use the recovery for installing a new os ....    
ClockWorkMod will overwrite your old recovery when flashing a new ROM,
So I'd suggest TWRP a.k.a TeamWin Recovery Project,
as TWRP will keep root and recovery installed when flashing new ROM  




If you still have trouble, Look up Unbrick any MTK Device ..

This takes you through the steps to installing a rom on any mtk device !



I would write more details but each rom needs specific installations !   



!   YOU NEED AN FREE ACCOUNT ON NEEDROM.COM FOR MOST MTK ROMs !    

Flash Files For SP Flash Tool for Z10    

Lollipop ROM for Z10



DO NOT USE FIRMWARE UPGRADE !
FIRMWARE UPGRADE WILL DESTROY IMEI NUMBER AND NV RAM ...

ONLY EVER USE DOWNLOAD MODE !    

ROOT YOUR DEVICE FIRST IF IT'S POSSIBLE !

ONCE ROOTED, USE MTK DROID TOOLS ( IN LINK [MTK REPAIR FILES ])    

AND BACKUP A FULL ROM ( INCLUDES NV-RAM, IMEI, SYSTEM, BOOT ETC....) 

USING A MTK DROID TOOLS BACKUP IS THE ONLY SURE WAY TO RESTORE NV-RAM (IMEI NUMBER - MAC ADDRESS )



MTK Repair Files
- SP Flash Tool
- MTK V-Com Drivers (generic)
- MTK Droid Tools        

If you can't access recovery, you need to use
V-COM Drivers, And Pre-Boot software SP Flash tools .... 

• INSTALL V-COM DRIVER FROM LINK ABOVE     

• Take out the battery ( power off completely )   

• Start "SP Flash Tool" and load the custom rom above by selecting the "MTxxxx_Android_scatter_emmc.txt" File    

• SP Flash tool will auto load rom from scatter    

• Untick preloader or Pre-Loader
( this is what you are flashing with )       

• Press on [ DOWNLOAD MODE ]  NOT UPGRADE!      

• NOW Plug in device and wait for download to finish and a green Tick to appear  √ 


IF YOU GET ERRORS, Please tell me,
I'll try my best to respond quickly !    




Errors    



"Device doesn't show anymore"
This is because you need to flash Pre-Loader again !
- Preloader needs fixing with SP MDT SP MDT.rar and the correct files. (preloader from previous rom) . You can use an old version of 
SP Flash tools Like V3 SP Flash Tool V3 to flash the old Backup of PRELOADER with MTK Droid Tools Hopefully ..

I have equal luck with both, If one doesn't work, the other does ! 

IF it still doesn't work and phone seems bricked,
You probably need to do a Firmware Upgrade, But this means you need SN Write Station and IMEI Writer to repair the IMEI, Mac adress, Bluetooth Adress etc ( On the original box or a sticker with the device )