Yes, this was the issue we talked about at Elasticon, and I'm glad you found it. The problem described earlier in this thread was most likely because the service took too long to start (on Windows a service must start within 30 seconds).
I've just downloaded the latest version of Elasticsearch (7.1.1) and given it a try, directly and not as a Windows service. I did this using the bundled JDK, though I had to set JAVA_HOME to it as Elasticsearch claimed to not have found the bundled JDK in the same folder.
Elasticsearch started in around a minute, which is not good enough but faster than I remembered with 7.0. Below is the CLI/logs output when I last tried to start it. I don't see anything obviously critical, though the gaps in time are not a good sign. Take a look, perhaps you may make more sense of it. Let me know if I can provide additional information to clarify the issue further.
OpenJDK 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
[2019-06-22T17:50:22,826][INFO ][o.e.e.NodeEnvironment ] [MYMACHINE] using [1] data paths, mounts [[Acer (C:)]], net usable_space [591.8gb], net total_space [912.7gb], types [NTFS]
[2019-06-22T17:50:22,841][INFO ][o.e.e.NodeEnvironment ] [MYMACHINE] heap size [990.7mb], compressed ordinary object pointers [true]
[2019-06-22T17:50:22,857][INFO ][o.e.n.Node ] [MYMACHINE] node name [MYMACHINE], node ID [ZgTn_njNTj-J_cc5YFR2Rw], cluster name [elasticsearch]
[2019-06-22T17:50:22,872][INFO ][o.e.n.Node ] [MYMACHINE] version[7.1.1], pid[10028], build[default/zip/7a013de/2019-05-23T14:04:00.380842Z], OS[Windows 10/10.0/amd64], JVM[Oracle Corporation/OpenJDK 64-Bit Server VM/12.0.1/12.0.1+12]
[2019-06-22T17:50:22,872][INFO ][o.e.n.Node ] [MYMACHINE] JVM home [C:\tools\elasticsearch-7.1.1\jdk]
[2019-06-22T17:50:22,872][INFO ][o.e.n.Node ] [MYMACHINE] JVM arguments [-Xms1g, -Xmx1g, -XX:+UseConcMarkSweepGC, -XX:CMSInitiatingOccupancyFraction=75, -XX:+UseCMSInitiatingOccupancyOnly, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.io.tmpdir=C:\Users\Daniel\AppData\Local\Temp\elasticsearch, -XX:+HeapDumpOnOutOfMemoryError, -XX:HeapDumpPath=data, -XX:ErrorFile=logs/hs_err_pid%p.log, -Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m, -Djava.locale.providers=COMPAT, -Dio.netty.allocator.type=unpooled, -Delasticsearch, -Des.path.home=C:\tools\elasticsearch-7.1.1, -Des.path.conf=C:\tools\elasticsearch-7.1.1\config, -Des.distribution.flavor=default, -Des.distribution.type=zip, -Des.bundled_jd=true]
[2019-06-22T17:50:32,107][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [aggs-matrix-stats]
[2019-06-22T17:50:32,107][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [analysis-common]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [ingest-common]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [ingest-geoip]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [ingest-user-agent]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [lang-expression]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [lang-mustache]
[2019-06-22T17:50:32,111][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [lang-painless]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [mapper-extras]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [parent-join]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [percolator]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [rank-eval]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [reindex]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [repository-url]
[2019-06-22T17:50:32,115][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [transport-netty4]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-ccr]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-core]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-deprecation]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-graph]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-ilm]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-logstash]
[2019-06-22T17:50:32,119][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-ml]
[2019-06-22T17:50:32,123][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-monitoring]
[2019-06-22T17:50:32,127][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-rollup]
[2019-06-22T17:50:32,127][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-security]
[2019-06-22T17:50:32,131][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-sql]
[2019-06-22T17:50:32,131][INFO ][o.e.p.PluginsService ] [MYMACHINE] loaded module [x-pack-watcher]
[2019-06-22T17:50:32,131][INFO ][o.e.p.PluginsService ] [MYMACHINE] no plugins loaded
The above is only part of the output. There is a 7,000-character limit to post here, so I'll paste the rest as a followup post.