Hi,
The HikaShop essential package work for new installations, updates and also upgrades.
You should be able to install it like an update.
About the blank screen, please follow the instructions in our FAQ (for blank screen).
www.hikashop.com/support/faq.html
About the installation, you might test to install the "zip" package (instead of the "tar.gz" one) or test the installation by FTP.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.