Shares of Rivian Automotive (NASDAQ:RIVN) are rallying hard after the electric vehicle startup received some good news. However, even a near 30% gain can’t cover-up the fundamental problems with Rivian stock.Rivian stock has increased 28% since mid-June on news that German automotive giant Volkswagen (OTCMKTS:VWAPY) is investing up to $5 billion in the electric vehicle maker. Investors have responded strongly to news of the Volkswagen partnership and cash infusion, but the recent rally can’t paper over the ...