As this video which has been linked at least twice--https://teslamotorsclub.com/tmc/posts/2624289/ and
General Discussion: 2018 Investor Roundtable -- states: "The answer is CASH!"
Tesla's "pipes 1 and 2" will require growing amounts of cash over the next several years if it is to achieve its expansion and growth plans (for instance GF-1 is less than 30% complete not to mention the investments needed in GFs #3-5+) Tesla's recourse is for "pipe 3" to continue to fill the cash bucket as pipes 1 and 2 extract from the cash bucket.
Pipe 3 has two sources of cash: debt and equity capital raises. Moody's credit rating downgrade effectively eliminates future debt raises from conventional institutional sources, until Tesla can demonstrate that it will generate cash from pipe #1 to begin repaying existing secured and un-secured creditors. Tesla does have about $700 MM in un-used commitments from the secured ABL creditors, but not only are LIBOR rates popping, but the entire line must be repaid or refinanced by June 2020. I'll leave it to those who have never experienced a corporate liquidity/refinancing crisis from the inside to assure there are no worries about a credit downgrade.
If new debt is difficult or unavailable that leaves follow-on sales of additional common shares from pipe #3 to re-fill the cash bucket.
Curious Sunbird offered his thoughts above in response to your question.
Market Action: 2018 Investor Roundtable
Wheeler knew cash is king--the credit down grade means favorable trade credit terms will be more difficult and likely consume more of the un-committed ABL line for LOCs. From experience, the decline in share price doesn't help internal morale when stock-based compensation is a meaningful part of remuneration for employees.